'97 Chevy c1500, 199k, v-6 AT. The truck runs fine most of the time, 3rd time this has happened; loses power spits and sputters but never dies.Idles perfectly smooth. Let it sit 15mins or so and it's great. Check Engine light has been on for 80k miles and no problem. Today it acted up, let it sit, and light went off. Mechanic drove it 4 days and never had a problem! (of course). He scanned the CPU and it showed Trans shift problems, but it has a new one. Light was on before and after that. I've had a new fuel pump and filter put on in August. Any ideas?

drivability problem is probably causing erroneous trans codes to set.... maybe an egr valve sticking wide open. egr will open once you are on the freeway and the trans is in overdrive(4th gear with torque converter locked up). thats tough to even start guessing, with intermittent conditions.

Ignition coil going bad? Corrosion built up in the distributor cap and rotor?

It's got me baffled. It will run fine for 2-3 weeks, then just lose power. The EGR sounds like a good start, I can smell a faint odor of gas when I have the window open.

Possible bad TPS. They can cause drivability issues & trans codes.

ahhhh. the faint gas smell.. sounds like you may have a fuel injector sticking/clogging up. might try and have a fuel injector service done with the high pressure machine.

Where can I get this done? I went to the store a few minutes ago, and it ran perfect.

I had a 99 that I could smell gas when the window was open and it would spit and spudder at ideal. It ended up being an O ring in the gas line was bad and spitting gass on the motor. Check the gas line where it gose into each cylinder.

One other problem I have seen is the fuel pressure regulator. The part is not too expensive just take the top half of the intake off and there it is!

Don't waste you money on an injector service, 60-66psi should keep the injectors clean.

Try some BG44K in a half a tank of gas, it will clean those injectors up.

There is an updated injector (spider) kit for these. It gets rid of the old poppet style injectors. I would start there and it comes with pressure regulator I believe. Hope this helps.

When you figure out definitively what the problem is, please let us know. My 1995 Suburban with a 350 is doing the exact same thing. No one believes me cause it only happens once in a while, never when someone is riding with me.

It quit on me last week, I sat in a parking lot for 15mins., started it, check engine light went off and it's been running great.

The 95 and 96 have different fuel injection systems. The fuel pressure is also different. I have seen many distributor pickups go bad in the distributor. . just an example. Can't be of much help without all the details as to what's actually happening when the engine quits.