Engine starts then stalls at idle

[grizzlyxjim]

So 99 v6 mounty, when I start it up it revs up but then the idle goes super low and sometimes it stalls. I have checked for vacuum leaks very thoroughly, I am thinking it may be the IAC unit but would like to hear what you guys think before I put money into a part. I took the IAC off cleaned it well, the gaskets were pretty chewed up. When I tried to run it disconnected it just died I read some where it was supposed to stay running even if it was disconnected. So yeah any thoughts on this

 

[RandomNerd2000]

Well you don't have a vacuum leak, so congrats on that one, considering the IAC and the fact I've never had one be exactly right after cleaning it, I'd just replace it, it's cheap and in my case, did better than either of my cleaned spare ones.

 

[GTMountain]

Making your own felpro gasket for the IAC is always a good idea. Last forever.
The only real check for a vacuum leak it a smoke test. $5 and 15min.

 

[grizzlyxjim]

So I am still having this issue. Haha. I replaced the fuel pump in july after it died and it fixed the problem for a while but started doing it again about a month ago. Replaced the IAC completely. I had the intake manifold replaced sometime in the summer too. No idea how I can fix this. any suggestions or experience?