1996 Nissan Altima, p0171

Hey everyone,

I recently got this code (p0171) on my 96 Altima (KA24de) and for the life of me I just simply can't figure it out. I am usually pretty good at finding what the problem is but not this time... SOOO I came to see if I can get from all of you. So my symptoms are, when I start the car cold and go for a drive, the car has hesitation under 3k rpm and the car feels like it lost some power. When it warms up it doesn't have the hesitation as much or you can *hardly* notice it (but I can cause I drive the damn thing everyday ) So here is a list of things I have changed on the car within a year....

MAF
Distributor Car/Rotor (No oil in distributor)
Coil
Spark Plugs/Wires
Fuel Pump
Fuel Pressure Regulator
Fuel Filter
Injector seals and gaskets (Injectors were good)
Front o2 sensor
Cat Converter (rear)
Starter
Battery
Alternator

And probably some little things I can't think of right now. Fuel pressure is ~38 PSI with vacuum and ~44PSI without vacuum and that is correct according to my Haynes manual book. No exhaust leak. I did relocate the battery to the trunk about 4-5 months ago, I checked all the wiring (4 times) and the fuses all look good so no shorts or anything. I tried to spray some carb cleaner around the intake manifold but it didn't really seem to change the idle at all and I checked all visible hoses I could get too and they all seemed fine. Anyone know what else I can look for or to do?

What years and models did Nissan have all the issues with intake gasket leaks? anyone?

I know about the infamous intake manifold gasket problem but I also thought it wasn't really a problem on the 1st gens..? I know for sure it is on the 2nd gen altima (98-01) but 00-01 the most. Any other way to check the intake manifold besides carb cleaner cause I tried that and it didn't make a difference in the idle. I also tried the smoke method and no luck there. I suppose I can try water and soap? Is there away maybe through pressure check or something?

Propane is the best way to find a air leak. With a scan tool watch the fuel trim numbers and when they go rich you found it. The intake gasket usually always leak on the #4 cylinder on the underside.

Inspect the air intake ducting between the MAF sensor ant the Throttle Body. Under a load, the torque of the engine will "flex" this ducting. If there is a slight tear in this boot (wear and weathering) pirate air could be introduced here. Take the boot off and bend and flex it. Can sometimes be hard to notice any possible holes or tears while its still installed. More than likely not going to be your problem but I have seen this overlooked many times. Good luck.