I boosted my car last month and it's been running fine up until now. My car idles right between 580-600 rpm. Every so often while at idle it drops to 300rpm for just a second and almost dies. Also there have been a few occasions I punched it from a stand still or a cruise, and the car stumbles, feels almost like the tranny is slipping.

I'm running the MP45 with the stock flash. I've replaced every vacuum line and gone through 2 bottles of throttle body cleaner checking for leaks. No codes and everything I monitor with a Tech2 seems normal, even at the exact moment a rpm drop occours. I'm kind of at a loss.

Sounds like it could be the TPS (throttle position sensor) going out - I had some simliar issues with mine and it took a long time to illuminate a check eng light.

Other things to check:

Plug wire connections can cause a mis or stumble (loose or corroded)

How's your fuel pump condition?