I have a 92 SSEI that runs awsome when driven short distances, but when driven for over a couple of hours I have a surging problem under any kind of load, part throttle and full throttle to the point where I could not quite crest a long gradual hill. The longer I drive the worse it gets. If I cycle the ignition the problem seems to improve for a short time.
I have removed the cat,replaced the plugs and wires.The coil was tested and ok. Can anybody help me out here I'm running out of ideas?
Thanks Bratt144

Define 'surging'.

Is it an increase/decrease in rpm'* on the tach? Or is it a stumble felt under load and light throttle? This is the key to finding the source.

It sounds like from your description of the problem that you might have a problem with the filter on the intake side of the fuel pump in the gas tank. It takes a few hours for the dirt in the tank to clog that filter then you start running very lean. It will cause surging and low power. If you turn the car off and let it sit for a time the dirt will fall off the filter and it will run OK until it clogs again. If it sits overnight it might take more than an hour to clog again. I worked in the dealerships for Pontiac for about 25 years and I have seen this happen more than once. This MIGHT be the cause of your surging. Hope this helps. BTW there is no test for this condition except to drop the gas tank and removed the pump and filter to inspect it.

stumbling might be a better description of the problem, the car will cruise just fine and under slight throttle will increase in speed but any excessive throttle and the car falls flat with no increase in speed or rpm.

The fuel filter in the the gas tank sounds pretty reasonable, i'm going to pull it out and inspect it. Any other suggestions?
Thanks Bratt144

If the problem is under light load in OD or climbing a hill under light load, you may be better served by replacing your plugs and wires, particularly if you don't know how old they are.

What brands of wires and plugs do you have?

this condition occurs under all load condions and in all gears the plugs and wires are new from GM

changed the fuel filter lately?