Ok, got a 95 blazer and a few months ago whenever I started it, it would run fine for a minute, then it would start idling erratic. It would fluctuate between 600 and 1100 rpms and would keep doing it for a few minutes until it warmed up. This happened every other time I started it. As of a month ago it does it every time I start it now and continues to run rough and will have no power and jerk around while accelerating unless I step on it until 3000 rpms. It would run like this until it warmed up more then run fine. I just replaced the engine almost exactly a year ago and has been giving me on and off problems ever since, this being the first problem since July when I replaced the injector AGAIN.

New parts include: Fuel pump, fuel filter, injector, timing chain and gears, distributor, cap and rotor, spark plugs and wires, ignition coil, knock sensors, MAP sensor, and TPS.

I have checked and cleaned both the EGR and Idle control valve and nothing has helped and has no vacuum leaks that I can find. I am at a complete loss, any help or suggestions would greatly appreciated before I pull out the rest of my hair.

Thank you!