car = 91 240sx

engine = rebuilt with 7k miles

mods - cold air intake/header/exhaust

replaced/switched out - o2 sensor, ecu, dist cap, dist rotor, ignition coil, Mass Air Sensor, spark plugs n wires, cleaned air filter, fuel filter, took out my audio system, battery, and ran new grounds.

After all that.. I started thinking about my TPS and just disconnected it and tried to run without the TPS harness plugged in. Car ran exactly the same.

Good at first, then slow after about 30-45 mins. I think it has to do with the heat, because my engine seems hot after long runs. If the engine is running slow and I get on the highway for a bit and get some air on her she starts running better. My temp is good, Always at the 3rd notch. Any ideas?

 

need to explain more.

 

um.. ok..

When I start the car up in the morning, the car runs fine. She pulls hard up to about 5500. After about 30-45 mins she gets slow. Really hesitant, stumbling. The more I press the gas, it seems the slower she goes.

I disconnected the TPS and the drivabilty didn't change.

Replaced/switched out are the parts that i have ruled out.

M question is, What is wrong with my car