chevy lumina van

Hi all, I need some help with solving the problem with my van.It is a 1993, chevy lumina. Runs good when I am driving down the road, as soon as I slow down to turn the corner it starts to chug. When I give it gas sometimes it will even pop. As soon as I get it at a faster speed it will come out of it. Seems like it is getting worse. Now when idleling it runs rough, It didn't do that at first, only chugged. We've replaced the fuel filter, plugs,wires distributor cap,egr valve.
It's hitting on all six cylinders. My son narrowed it down to an electronic problem. All advice and suggestions are welcome. Thanks, Andie

I'm the proud owner of TWO '91 Luminas. An APV (195,000 miles) and a sedan (270,000 miles). I have the same exact problem with both vehicles but I haven't found a solution yet. I think it is an electrical, rather than fuel problem, because the APV is carbureted and the sedan is fuel injected. I've also replaced almost the entire fuel system on both vehicles and I still have the problem. Because the stalling has the exact same symptoms on both vehicles and occured roughly at the same time I thought some prankster has put sugar in both gas tanks as they sat in my driveway. In fact, from the fuel tank to the fuel injectors, everything but the fuel line has been replaced on the sedan and all but the line and carb on the APV.

I can check the spark when the vehicles are parked and it is fine. But the stalling only occurs when I'm out and about. Just like a kid who only misbehaves when it is away from home.

I had a fault code 34 (MAP sensor out of range) and a fault code 45 (oxygen sensor number 2 rich exhaust signal) on the sedan. I think these codes appear only because the spark fails and the vehicles choke on the raw gas moving through the engine and exhaust system.

Both batteries are new and the alternators have been tested and are fine. I've replaced the crankshaft speed sensor on the sedan. It was leaking oil but its replacement had no effect on the stalling problem. On the van I've replaced the transmission lockup torque converter (solonoid, pump kit, and switches). That actually helped for a few weeks but the problem is renewing itself. In that case, the stalling at high speeds may have somehow damaged the lockup torque converter rather than the lockup torque converter being the cause of the problem.

I've put new sparkplugs and wires on both vehicles and a new distributor cap on the APV. The APV doesn't have an electronic ignition, like the sedan has, so it has a distributor. Again, they have same exact stalling problem so I'm guessing that the problem has to be something common to both vehicles.

I know this doesn't answer your question but you might not have to try some of the expensive (and worse, time consuming) things I did.

Thanks for all the info. My son was going to put on a map sensor today and drive it to work. I won't know if that is the problem till tomorrow but will post as soon as I find out. Thanks again. Andie