Weird idle
 

So for those who remember I recently put a new motor in my 98 2500 an everything has been great an going smooth
Until now I keep getting this weird idle on a cold start the rpms will fluctuat between 600/1000 rpms for no apparent reason.
Now I've ran into the issue before with the rpms much worse like 500/1500 rpms an discovered it to be the TPS when I replaced it the issue went away I also did the IAC at the same time.
This also doesn't just happen on a cold start, itll happen after its warmed up if I rev the engine a few times the engine will start to stumble like it wants to die.. Pretty weird because the trick never skips a beat EVER


I'd appreciate any help/input anyone could add to my situation

Weird idle
 

Intake leak?

That's what I am thinkin'. Acts a lot like a vacuum leak somewhere.

Weird idle
 

Check all the vacuum plugs on the intake. They tend to crack from heat

Is it only on idles or does it want to die when driving at higher speeds? If it's at higher speeds check for a clogged cat.

[QUOTE=alaskaguy;3265017]Is it only on idles or does it want to die when driving at higher speeds? If it's at higher speeds check for a clogged cat.[/QUOTE

Yeah only at an idle, I replaced the cat when I replaced the engine like 5000 miles ago.