"90 Cav. Occasional bucking & a code 24

[Griffdaddy13]

Hi all. I've read many threads with similar problems. Unfortunately, no one seems to post their solutions. For a while my Cav('90 with a 2.2) Would buck a couple times then just die, usually about 7-10 miles out. Sometimes no bucking first. Sometimes it would buck a few times then smooth out & run fine for the rest of the day. When it died I could usually start again in about 15 minutes. When it died at highway speed, I could keep it running for a little while by flooring it, but it sounded like it was starved for fuel & would steadily deteriorate & start to backfire with strong sulphur smell. I thought fuel pump, but apparently not. Pump seems fine, although I did replace pump harness in tank. I have also replaced ECM, Ign module, coil packs, MAP sensor, fuel & air filters. injector is fine. I've added injector cleaner, but haven't tried high octane. Car hasn't actually died in 2 weeks, but still bucks now & then, usually in first 15 min on road. ECM was last thing inThis seems to have stopped the stalling. Now getting check eng light when first starting & code 24 when running diag. No codes before new ECM. Chart says "Between 1200 & 4400 RPM's MAP signal showed low voltage (high manifold vac) for at least 5 seconds. Generic GM code list shows 24 as Speed Sensor, which I haven't found on any parts store websites. Not sure if it exists on this car. Any ideas?

[slf41002]

I didn't see were you said anything about the catalytic converter.Have you checked it?

[Griffdaddy13]

Thanks for your reply. The Cat's relatively new, and this really doesn't act like a bad cat. I found one manual that lists my code as "Vehicle Speed Sensor Circuit" only. I guess that's my next step. Please let me know if you've got any other ideas. Thanks again.