Hello everybody, it’s been a while since I’ve used the site but I’m back for more help lol

so I run a shop in Va. customer brings me a 96, pretty stock more or less. Complaint is it stalls when decelerating. And only when decelerating. So I thought iac, or something vacuum related. Checked old iac, sorry as all get out, but replaced it anyways because it was pretty cheap and the customer thought it was a good start anywho. Cleaned TB while I was at it, and checked map/fuel pressure/ tps readings as well. Everything checks out at idle, and under throttle all is well. But sure enough, drive it a few minutes (between 2-5) and when you come to stop, sometimes, and only sometimes, it will act as if you “left it in gear” and stopped. No shudders, no bogging, just pffft. And she’s off. Put it in park, crank and crank, and will finally start with feathered throttle, but act as if nothing is wrong until it stalls again. I double checked all sensor values KOEO and running, all except the cps which is tomorrow’s plan to check. Just seeing if anyone has any ideas? If the cps checks out I guess I’m chasing pcm wiring or a bad pcm at this point 🤷🏼‍♂️

 

Maybe a restriction in the exhaust? Or CPS.

 

Same year. It could be a bunged exhaust. My cat had come apart internally and was partially blocking the exhaust. It rattled at a certain RPM inside the cat. I thought I had a bad clamp causing some metal-metal vibration but all clamps were secure. I replaced it and performance increased. I replaced the cat and muffler together with a new aft O2 sensor, old sensor being seized.

 

While I could definitely see the exhaust being restricted, it’s not following that path. I mean it runs flawlessly up until it dies. That just doesn’t make sense. Plus there is no exhaust sounds that are abnormal other than a small leak at the muffler.

 

I had almost identical symptoms, ran fine till it stalled, and I'd have to crank it for a while with the gas floored. Once it started I'd need to keep the gas on for a while till it ran perfect again. I replaced almost every sensor, and each time I thought I had the problem licked, till I didn't. Then one day I noticed a crack in the exhaust manifold. I figured something about air entering there would trigger a flood of fuel from the injectors causing a stall, blah blah blah... put a *****ing ss header in there and never a problem since. Long story short, check exhaust for big leaks and holes

 

I dont know where that profanity came from oops. Sorry

 

So, while checking the cam position sensor and dizzy in general. I pulled the rotor button off, and noticed about 1/8-1/16” play in the shaft of the dizzy, and the rotor was chewed up for lack of better wording. Ordered a new dizzy, slapped it in and timed it, voila, no more stalls or hard starts! Kinda weird and definitely not what I expected, but hey, one to keep in mind!!

 

Wow, good one to keep in mind - super appreciate the follow up!

 

I'm not surprised. My first thought was a timing issue. I was going to ask if the owner replaced the distributor recently.