Chevy & GMC Vans

I've owned my van for a week and have driven it twice. I dont know much about the history of it but was told it had heads replaced due to an overheating issue. My first thought of the poor running condition is that it needed a cat converter. I cut it out and it was clean. I then changed the fuel pressure regulator and the coolant temp sensor. It runs fine for about a half an hour then feels like its loading up, doesnt want to go over 30 mph and it almost sounds like the engine is being choked. Any ideas ? possible exhaust clog ? cant understand why it takes 30-45 mins for it to start running poorly when it gets up to temp in about 5.

post the year model of the van, it will help with responses....

Sorry... I thought I had done that. Its a 2000 4.3
Pulling my hair out on this one. Today I changed the plugs, wires, cap and rotor and it still runs like crap after about a half hour of driving. Any help is appreciated.

had full sized van w/around 300,000 miles on it, that acted that way, but it died before I figured it out, I was thinking loss of compression, might try testing it...

Any SES codes? Does the light work? If the converter was bad you should be getting a PO420 code. I would have to think the ignition coil would be warm/hot enough to start acting up after 1/2 an hour of driving.

The fuel pump may be getting warm and binding after running for a while.
They don't always go bad and stop all of a sudden.
I had this happen on another vehicle.
I was able to attach a fuel pressure gauge to the fuel rail and tape it to the windshield
and watch the pressure while I drove.
When it started acting up the fuel pressure dropped.
It would idle fine but run very rough under a load.

Thanks for all the help.... I finally got the codes, P300, P172 & P175. I changed the left front O2 sensor and the coolant temp sensor and it runs great now.

Glad you got her running great! =D>

stevieb wrote:Thanks for all the help.... I finally got the codes, P300, P172 & P175. I changed the left front O2 sensor and the coolant temp sensor and it runs great now.

Good to hear stevieb, and thanks for letting us know the outcome. Hopefully that info will help someone else down the road