what about the cat ?

 

My car is sort of doing this too... when i first start the car if i dont let it warm up for like 3-4 minutes and start driving it the idle is pretty high, it goes back to normal once that car warms up and it goes into the closed loop thing and the check engine light comes on... when i say high it idles around 1300-1500. the only difference is that mine still seems to have its power while its idling high. btw this doesnt just happen when its cold out it was doing it this summer when it was like 90 out

 

If there are no trouble codes, and theengine is not misfiring, I don't think it has fuel or ignition problems, However;you can check the fuel pressure and pressure regulator very easily with a $25 fuel injection pressure gage. There is a sticky in the LT1 section on how to do it. My SWAG is that th cat is clogged. You can test the cat by disconnecting it from the Y pipe, and see how the car runs, or by doing a back pressure check. This is doneby removing one of the O2 sensors and sticking a back pressure gage in its place, run the engine under load and read the pressure. Anything over 5 PSI is suspect.