Hello everyone, I am new to this forum, I have a question I have had no one able to answer for me. I have a 1996 Eclipse GST, engine has a new air filter, and 3" down-pipe back exhaust. Other than that is completely stock. I replaced every vacuum line in the engine, as well as a MAP sensor that went bad. As far as I can tell, I have no vacuum leaks, and have gone through and tested most every other sensor that can adjust idle...

When the engine is cold, the idle is horrid. Even at WOT the engine will only sit at 1k to 2k and misfire, most of the time will drop down to about 200rpm and then spike back up smooth for a minute. It will continue this until the engine reaches normal operating temp. Then it will run mostly smooth with a slight hiccup.

I took this video tonight in hopes someone has seen this before.

What could cause this? - YouTube