My engine is a 305 TBI 92 RS. I've been getting a "stumble" while warming up, and when I'm driving. It seems to occur when it is raining, or just rained. I've replaced every sensor under the sun in the last couple of years, EGR included. I'm not getting a check engine light either. I suspect the coil, but I'm stumped. Any input would be appreciated.

 

Can you elaborate on what you mean by "stumble"?

 

I'll give it a shot: When I am driving, and the engine is warming up it will hesitate, run right briefly, then hesitate, then it clears up about when I go into closed loop. I have almost determined that moisture is a factor. When I get a dry spell, I don't have the problem. When I accelerate it seems to behave better than when I am driving slowly. When I pull out on my road, or creeping through a parking lot is when I have it. Most of the time when I start and drive, I can't go fast due to where I am driving.

 

I had this same problem with my 89 camaro. Replaced the same sensors, distributor, etc. , I put a hose to the engine bay and sprayed areas until it started to stumble. It ended up being a wiring harness that went along the passenger side cowl , I followed it down into the passenger fender and from there it went into the passenger side interior and under the dash. I pulled the wire loom and the plastic inner fender cover off and where it passed into the interior the coating on the wires was bare thus causing a short when water got on it. I chased this problem for 5 years.

 

Just to let you know, one if the as wires coming off the IAC pigtail was against the EGR. It was burnt with wire exposed. The issue comes and goes, but it hasn't stumbled yet. Maybe this was causing my issue. I'll see how it goes.