So I have a 94 Chevy k2500 with the 350. I bought it used with 180k on it but it runs like a top doesn't burn oil, doesn't even have a leak. I do keep getting the occasional IAC code... Which I've tried to correct but have had no luck. I have replaced the IAC, checked the wiring harness(no issues there) and even tried to adjust base idle(the cap for the idle adjustment screw was missing when I bought the truck) I can't seem to get the base idle down to what the instructions say(I "seat" the IAC then unplug it and screw the idle adjustment screw all the way out and still can't even come close to the 600rpm mark.) I am beginning to wonder if my throttle body blades, and/or my throttle body bores aren't worn out enough that, no matter the adjustment, the idle is going to be what it is, I believe this because I've smoke tested for vacuum leaks and have found absolutely none.) Also I have somewhat of a voltage issue, it could be the gauge though... My voltage fluctuates between 14-12 fairly rapidly, and the hotter the operating temp gets the lower the voltage gets, so at operating temp it reads more like 12-10 volts....either way these are what I believe to be secondary issues, but I thought I would give for relative information....
Anyways the issue at hand is I have very little to no low end torque/power. It takes for ever to accelerate and reach higher rpms(I can floor it and it is no different acceleration wise if I give it half throttle.) As well as the fact that I have a 4:10 rear end so I should have loads of torque, especially, over a 1500 of the same year(which I have driven/owned before) and that's simply not the case in my experience. Let me put it into perspective.... When trying to power brake it( I know that's bad on the tranny/torque converter...but for testing purposes) with the pedal to the floor it will not go past 1800 rpms and won't spin the tires no matter how hard i try. Something is wrong, it's not throttling up like it should like any other 350 I've ever owned does. I'm not quite sure why, or where to start. I thought maybe a plugged cat... But I took out the o2 sensor and drove it and there was absolutely no change. I just want the power that I am being robbed of to be restored. Thanks for the help.