1987 Trans Am Idle Issues

[lindyh87gta]

Hi! First time poster.

Hi! First time poster here. I have a 1987 Trans Am that I had fully-restored about ten years ago at Hawks Third Gen in Easley, SC. Driven lightly but regularly since then, garage kept on a trickle charger. No issues since the restoration and only lightly driven until recently. I've been driving it more this year, and am trying to fix an issue with the idle. Hoping to get some advice here.

It was stalling on idle, so I just replaced the mass air flow sensor and IAC valve. I also made sure to reset the IAC valve after replacing it. It cranked right up and was idling well, so I took it around the neighborhood to see if there were issues. Drove well. Rev'ed the engine in park a few times, too, and the idle returned to about 800rpms every time.

I put it back in the garage and turned it off and cranked it again a few more times. When I'd let it idle in park after turning it back on, after it had time to come down, it rev'ed between 500 and 1000rpms a few times before settling back around 800 rpms. This happened twice. It didn't stall, so that's good, but I'm wondering if that's normal as it's adjusting to the new parts or if I should be concerned that there's another issue.

Any advice?

Pic for tax
drake.jpg

[maxwedge]

Welcome to AF. Tuned port 5.7?

[lindyh87gta]

Yes. Car is an 87 GTA, but engine/trans are a 350 5.7L TPI out of an 89.

The MAFS was a cheaper aftermarket that I bought since money's tight right now, but after the rev'ing started, I used some MAFS cleaner on the old one that I took out, which is a Bosch. Rev'ing stopped, but some of the original issues came back (slower to crank and smoked a good bit when I cranked it up; both had stopped with the new MAFS). Was able to take it a few miles down the road and back with no performance issues, so I think it's holding up, but just bought a Delphi MAFS to hopefully be done with it. Will return the cheap one and keep the older Bosch as a backup in a pinch.