I bought my truck about a year ago, a EFI 22R. The truck has always had a "lack" of power, but I've noticed that when I first drive the truck (cold) it seams to have good power, but when the RPMs get to about 2200 it has a sudden loss of power and at the same time the check engine light comes on. Always at the same RPM and more pronounced when cold. I have replaced the timing chain, PCV, cap, rotor, wires, and plugs with no change. I have also changed air filter and cleaned the MAF sensor. Could the fuel pump or fuel filter cause these symptoms? Or O2 sensor? Any help would be most appreciated.

 

It would be a good idea to replace the fuel filter, but you also need to pull the codes to see whats wrong with your truck.

 

Pulled the code and found it to be #12- knock sensor.