My van (95 GMC Vandura 2500) has been having issues off and on (lately most of the time) for the last 3-4 weeks with running properly. Initially it would rev and wane, causing hard shifting (automatic tranny) and difficulty getting up to and maintaining speed. We changed spark plugs and wires, distributor cap, air filter, changed oil- did not work. Took in for diagnostic- they said TPS was bad. My son replaced it and it improved the reving but now it acts like it is not getting enough gas/ steady supply of gas (will buck when starting off and then occassionally when trying to get up to speed, will die when I slow down or stop or put in drive, I need to push the accelarator way down to get it to go faster ) The engine light will come on after a while of this. Some mornings (I do a paper route) it will die 5-7 before even making it out of my driveway and several times while delivering. We thought the TPS we installed might be faulty, so replaced it again- still had the problem. Changed the PVC valve and the fuel filter- still acting up. The odd thing is it is not constant. Like yesterday- in the morning during paper route- ran badly- died 5 times- did not want to go over 45. Then that afternoon I had errands- 4 hours I ran all over- interstate included-it ran great. Ran great this morning during paper route- then this afternoon took son to work then on the highway- it started in again. I drove to AutoZone where they said I needed to unplug the battery for 5 mins- as the computer was still thinking the old part was in, then reconnect it. Did that. As soon as I pulled out of the parking lot it acted up again. My mechanic cannot get me in until next week and I depend heavily on the van- its my only vehicle and I live in the country and my husband is living out of town for work. My teenage son can do most things with the van if I know what the problem is- any ideas? BTW the current engine (I blew the last one from forgetting to change oil) has about 90,000 mi on it- tranny replaced about 60,000 mi ago, the engine is a 350 5.7 liter.