Thank you for your replies! Yes... I Tried a myriad of combinations of manual shifting and time and again trying full regular automatic. Finally getting back on the Florida flat lands, I was managing to carefully "tease it along" at exactly 62-63 using cruise control in regular 6th full automatic. It seemed the CC could react quicker or feel the nuances of the situation better than I.

I would think this was all normal with the weight and drag of the trailer on a 6 cylinder engine with 110,000. Except it performed so well just weeks prior on the way north for the full 1,550 miles!??? And all the work I did while up North was to replace the defective heater control valve. (If you have the optional rear heat controls, remember you must buy the -two- solenoid model. These units can be rebuilt as well. Easy repair with only a screwdriver, and you DO NOT need to go under the car as a Utube video states! Take one hose off that you can get to with the screwdriver, then twist and lift off the mounting pegs, and then twist to access the other screws on the hoses. Ebay sells rebuild kits for $55. Sure enough when I looked up the hose ports, I could see mangled rubber remains in 2 of the ports, blocking the hot water from getting to the heater core. Diagnosis: Put heater on high full heat full fan and you will feel the 2 hot hoses coming in, but the output hose running to firewall will be cool or only lukewarm instead of hot. Very common failure item. It was frozen HELL all the way from Atlanta North to Wisconsin with no heat!!! (;

I jacked up the trailer today and -removed all four wheels- and tires and did a 5 wheel rotation using the spare (since I had it up anyway). I was hoping to find a tight wheel that did not spin freely, but all had only slight resistance, just as manual states they should. The manual states to adjust them loose, then retighten to where they have slight drag. I know the brakes with the new BMW controller work outstanding so I left well enough alone.

I opted for the Haulmark trailer mainly with going to or left sitting outside in winter up in Wisconsin, the fact it has a ONE piece aluminum roof. No joints to break open from vibration on the road, and then leak later. But it also had the radial tire option which the old guy who owned the trailer yard for 30 years said he much preferred due to a far less chance of a blowout with radial tires. Radials last far longer too.

But overall I'm disappointed with seeing rust already here and there underneath and along the tongue. Haulmark could have done a much better job with paint. So I really let loose with my WD-40 pumper underneath, soaking the springs, door hinges, etc. (It's really a life saver down here in Florida with the salt air and high humidity. I wipe down my tools and yard cutters, etc., after each use. Great stuff for what is basically kerosene! Far, far cheaper by the gallon, and just use a pumper bottle. I use at least a gallon a year).

So any crazy ideas? All thoughts or ideas no matter how improbable would be appreciated at this point!

This may be something to note.... When I'm working in the garage, I hear "something" kick in and run for about 5 to 10 seconds maximum, then stop. I've never timed it, just happened to catch it while out there. Would that be the fuel pump? I know my exact model and year did have a recall on defective fuel pumps in Oct. 2010. Was issued for the E70 3.0 liter N52B30, 6 cyl gas engine. Manufactured 11/1/2007 through 8/31/2008. Replace fuel pump, defective batch during that period that could fail and make steering and braking difficult. Mine is a 4/08 build. Not sure if mine has been replaced under the recall? --Could a weakening fuel pump due this???-- Again...full power running around the gas stations at the exits, and going up the on ramp, but hit 60 and transmission has shifted normally through all the gears, but in 6th (top gear, 6 speed in E70) it bogs down and often shifts back down to 5th. Speed falls off fast in 6th you push the gas pedal down, down, waaay down, and you lose speed and it does not like it one bit, but ease way up on pedal to around the low 60 mph area, and that is it, period! Like someone turned a switch off at 60!

But we know the power is (or was) there from our -very strong- run North with another 1,500 pounds in the trailer! Again...we were very pleased with the power, more than enough.

1. Fuel pump weak?
2. Could I have developed a vacuum leak in an intake hose or in the CCV system? On my wife's 02 330i, she had the cracked intake hose way back on the driver's side by the firewall, where the hose made the bend and was "corregated" but when you looked in the bend, there it was, a 1/2" long crack! Also the CCV hoses were all brittle. And the one to the dipstick (don't I wish a dipstick!) (; was fully broken off. Now when you pull out the dipstick, you can easily hear a noticeable "Thump" when the vacuum breaks by pulling the dipstick.
3. BTW... I had just changed the auto tranny oil (new pan with 7 liters of the ZF fluid, and the transfer case oil (BMW brand) B4 hitting the road. I was getting a scary (1 out of 30 times on normal startup in park) light "clunk" but also the vehicle jerked back an inch or so." That worried me, and I bet the very reason the PO sold the vehicle. The new transfer fluid fixed this issue to instead on vary rare occasion just like someone snapping their fingers, but zero jerking motion.
PS: I tend to get off topic, but when I can help others with issues they may experience, I toss them out there. I apologize to those that don't appreciate these tidbits along the way. (:

Any ideas fellows? The winner with the correct answer gets a neat century old Morgan silver dollar sent to him as a -Thank you- for helping! I do appreciate your time to read all this and any help you can offer! Thank you. (: