My 94 Chevy Silverado throttle body 350 runs good, but when I get on it. It acts like it is going to die. If I hold my foot on the gas it will spits and sputter then takes off with a lot of power. The rps will drop almost to nothing then spike. If I take off slow it will runs fine. Why is it wanting to die when i give it gas?   I have replaced fuel lines, tank, pump, sending unit, plugs and wires, distributor cap,coil, and throttle body sensor. Can some one help I'm not sure where to go next. I thought about going to a junk yard and getting sensors and anything else I can get my hands on. And replace one thing at a time to see if I can fix the problem. I'm willing to take any and all ideas.  

I have a 94 gmc 4x4 and I also have the same problem, I have changed all of the same components plus a computer, distributor,injectors map sensor,and knock sensor. I'm still stumped.    

When  and under what conditions did this problem occur? how much exhaust is coming out of the tail pipe at WOT?   Bad/restricted cat?  

Mine has been this way since I bought it, I have swapped motors(thought it might have been a head gasket) and just about everything else since then with the same results. I have no cats, I thought of that and replaced the factory cat with a glass pack and still retained the factory muffler. when it starts stalling I can hammer it and it chuggs for a split second then it comes alive again.  

I also have swapped motors in my truck and I was still getting the same result. I didn't think about the cat. I will try messing with that. I did replace a couple of vacuum lines and it did help. But know it is starting to act up again. A couple of nights ago I hammered it and the truck shut off on me. My head lights and dash lights were still on, but the battery light also came on. I slipped the truck into neutral and it started right back up like there was nothing wrong spun the tires and took off. It has also almost died on me as I was turn at a corner. I slowed down made the corner gave it a little gas and nothing. RPMs dropped to nothing for a few seconds and then it is like everything catches up and the truck has more than enough power to set you back in the seat. Could a bad ground wire cause any of these problems? The conditions don't seem to matter. Warm or cold weather the same thing happens. Let the truck sit and warm up or take off cold the same thing happens.