Well this happened a bout a week ago when it snowed and last night it rained a lot.

Im guessing something is getting wet, when i start the car the rpms jump from about 500 to 1500 and just keep going up and down, won't idle.

when i give it some gas rpms drop to about 200 then jump to about 3000..

100 percent stock with 61k miles.

last nigth on my way home car had no power after 4k rpms and shook big time.

Last time it did all this it sat for about 10 hours while i was at work and when i came home it was running perfect..

 

https://www.cobaltss.net/forums/2-0l...inally-116051/

this might fix your problem.

 

it was a rusted/ wet MAF sensor, guy before me did the air box mod i guess and threw a filter on it and filter was soaked and intake was all wet inside