Lots of work done, still P0171, P0174, P0155

[Heckler]

I recently just replaced the following:

Valve cover gaskets
Valley pan gaskets
Upper timing cover gaskets
Vanos solenoid seals
Intake manifold gaskets
Both End caps on Intake Manifold, every gasket from the back to the air filter
OSV and all related hoses including the lower ones to the oil return pipe
Secondary air line o-rings
New spark plugs

Everything else was inspected and cleaned... Now what?

The only thing I can think it could be that has never been replaced are the 02 sensors, MAF, and fuel filter.

Any ideas? I already dumped a lot of coin into it, if I have to buy any more parts that dont fix the problem Im going to hook that Bitch up to my F350 and drag it around the desert!