Wierd surging problem

Today I changed the Throttle position sensor and Coolant temp sensor to see if it would solve the poroblem and it did not. Tommorow I will put in a new fuel filter. I have also changed out the spark plugs. I have a 1988 GMC s15 2.8 v6. Anyone have anymore ideas? It almost like it is shifting from drive to overdrive really quickly back and forth.(That is just how it feels, I don't know if it is really shifting) The rpms move up and down less than 100rpm's.

You need to find out if the TCC is engaging and disengaging or if this is an ignition or fuel problem.

While driving, when the surge starts, lightly press on the brake pedal and see if the surge goes away

Okay I will try it. Should I keep my foot on the gas as I push the brake? Also, What does the TCC stand for? Thanks again.

Okay I lightly pressed the brake while it was surging and it went away. I mean I could just barely touch it and the surging would stop. Does this mean I need a new TCC? How big of a job is this? Really I am just so happy to have identified the problem! LOL

TCC is the Torque Converter Clutch which is part of the transmission torque converter.
You will have to remove the trans to replace

Thanks. That sounds expensive. I have to go to sleep and blow off some steam now seeing I just bought this to get away from my VW's high maintenance costs.

Oh yeah. How long can I possibly drive this w/o seriously causing problems? I can handle slightly pushing the brake for a while.

Don't do that..you push the brake pedal, you apply the brakes

okay, I'll get it looked at immediately. Thanks again.

I have been doing some research and had another question. Is there a TCC sensor or solenoid that might need to be replaced? Also is there a fuse that controls this sensor that could be bad also?

If the fuse was bad, the TCC would not engage.
it is possible that the solenoid could be going bad, but the clutch is weak and can slip causing a surge

I see. The guy I bought the truck from works next door and he said he put a new transmission and TCC in so he said it might be under warranty. I am really more worried about the labor than the part. Well as part of the deal he installed a new haeter core for me yesterday. He had it b/c it needed to be replaced and he never got to it. What does a heater core do?

Problem fixed. I failed to tell you b/c I didn't think it mattered was that the speedometer was broken and the needle moved eradically. Well I found out the TCC gets readings from it and this was causing my problem. So I went to a junk yard and got a new speedo head and it fixed it! Thanks again