94 Help flat @ 2400 rpm

I have a 94 2500 5.7 4spd manual. The truck hasnt run right since I got it. I need help! 1st, the idle fluctuates when cold. Not bad when warmed up. 2nd- the worst part is the truck falls flat on its face @ 2400rpm. It will go past it, but very slowly and then pick back up. Its got no power above that and driving me crazy. Ive changed plugs, wires, tps ,IAC , checked egr and the guy who had it b4 me said he had the distributor changed to fix the problem. Sold the truck to me still with the problem. In neutral it will rev to the sky, only under a load does this happen. Any help? Truck doesnt throw ANY codes! Thanx in advance, great forum ! Jeff.:mad:

Welcome to AF, blocked cat, low fuel pressure, clogged fuel filter, only one injector in the TB working, all possibilities.

Both injectors seem to be spraying looking with timing light, fuel filter is also new. Im wondering if the fuel pickup sock in the tank may be clogged? Every once in a while it WILL run normally past 2400 rpm but not often and to me power seems down quite a bit for a 5.7 manual.

A lot of possibilities. Could also be more than one particular thing as well. The two things I would start with are the TPS and the O2 sensor. The TPS for the erratic revving and the O2 for the loss of power. If it spits and sputters when you hit the accelerator, that can easily be a clogged cat as well, just as the other post suggests. Start with all the cheap stuff and work your way up. If all this does not work, then move on to the cat and if still having issues, the pick up coil is a likely culprit, but that can get pricey if you do not do yourself ($5-800 for a mechanic). This assumes you have tried the other suggestions, all sensors and the vehicle is properly timed but you still have the problem.

Timing is spot on, cat doesnt seem clogged, I have alot of exhaust coming out the tail pipe and seems to be flowing freely. I might add I changed the tps, the cts already and the problem still exists. Doesnt matter what gear its in its always at 2400 rpm when it happens. If you hold down the pedal anyways, sooner or later the truck picks up again but not with the power it should have. Is there a way for me to set up the tps at home?

The key to the diagnosis here is to check FP when this is happening.

If fuel pressure is good (need a special tool to check it), the ignition coil should be checked.

//2000CAYukon

Fixed ! Changed Egr with a GM valve, a bit better but not great. Also, punched out the plug on the cat. A little better yet but still not good. Finally while pulling the trailer camping the truck after an hour could barely keep speed I had enough and dropped the tank. Put a new delco pump, and new sending unit in and PERFECT ! Truck runs better then ever! I thought a fuel pump just dies, but know I know, they can gradually lose volume and still work . So 300 bucks later and its all good. Hope this helps somebody else with simalar problems. Oh by the way, original pump with 320000kms !