94 GTP 3.4L rough Idle when cold

Hello... first post here. I've searched for the answer to this problem for about a year now with no luck. I've got a 94 GTP 24v 3.4L with 80,000miles. Two years ago, engine started revving at cold start from about 2500 rpm down to about 500, almost dying. I took it to the local mechanic, they ran tests and found nothing wrong. Of course, it started perfectly when they tried. I took it to another mechanic, he cleaned the egr valve, and that fixed the problem for two weeks. It happened again, along with error code that pointed to the egr so he replaced it. That fixed it for about three weeks, got rid of the error code. I gave up on the EGR valve... and the car ran better over the summer. Now that it's cold again, I'd say about half of the mornings I start it, it acts up. It's actually died a few times from this. The problem is always fixed after I drive it for about three minutes, and it only happens in the morning, espically in the winter.

Sorry for the long post. This has stumped mechanics around this area for a while, so I wanted to be detailed. When it is acting up, it pretty much drives itself down the road when in gear... and if I choose to hit the gas, it's really unresponsive. Fuel pump? Intake valves? Help!