That stuck T-stat is absolutely causing the starting issue, and possibly the enrichment issue which is leading to misfires.

It's going to run like crap if it never warms up man.

The starting issue is new though. It didn't have it before. Would this in the end be causing my low power issues from the video I posted? I was planning on doing the T-Stat this past weekend before it had these new syptoms so if that is the case, I can do it this weekend if it will fix my performance issues.

Recommend after you swap the T-stat go on a good 10-20 minute highway cruise in 4th gear. Beat on it a little if you can give it load. The idea is to burn off carbon and condensation.

Edit: I would wager the next cold start after that will be better. Might sound kinda silly, and hell, i could be wrong BUT I've seen that symptom/fix before.

you've got t-stat, road speed and MAF... the MAFs could be from last time you were messing with it... road speed - that could be secondary to the engine speed not matching up to the rest of the car... misfires could be secondary too but it could be due to you previously messing with fuel rail... most of your issues are at 343K kms, which is about 200K miles - find exact number that shows up on your odometer, to figure out when it happen - even though it is not that important... save the error files, clear them and see which ones will return, concentrate on those...

t-stat should be relatively easy to replace... did you unplug it from before? if you did, it could be left over from the last troubleshooting....

He got a P0171 and P0174 DTC. Kinda doubt if a bad thermostat will be giving him those codes. In fact like you mentioned that a cold thermostat will cause the engine to run rich.

Either a vacuum leak (could be from the injectors he removed but didn't replace with new o-rings) or a clogged filter or bad fuel pump. He replaced the filter and fuel pump so that just leave the injectors as a possible source for the vacuum leak.

To Quote Mr. Spock

" If you eliminate the impossible, whatever remains, however improbable, must be the truth. "

I erased the codes, and am at work today (drove the car) So I will try to see what new codes pop up after a day's worth of driving.

I reviewed that video you posted earlier on the "fuel pump" removal and tips, and did not clean the tank down before installing a new pump (in fact, my gas tank had fuel in it both times I replaced the pump. According to the video, there are times where a bad pump could actually leave metal shavings that could clog the fuel filter and cause problems. I hope the fuel filter isn't clogged again from something I didn't check last time.

As for your recommendation, I'm going to try to see if I'm not losing any type of fuel pressure at the fuel rail connection, and the injectors. The fact that no OBDII codes are coming on is starting to bother me.:dunno:

It won't solve those codes BUT, that's where he needs to begin, so he can get off of the warm up map and improve cold starting.

One step at a time.

Whether the thermostat causes any condition, lean or rich, I would replace it first as it has to be done anyway. It wouldn't be the first time something that there no way it can be connected to the problem turns out to be the core cause.

Spock has Spock-en!!!:iagree: