VW 02 Jetta

My 02 Jetta gives me grief when it is sitting and it is misty or damp overnight. it misfires and shakes, lately is seems to be getting worse the engine check light comes on and when i drive is flashes. As soon as the car warms up it runs better. Does this problem have to do anything with the engine itself or is it an ignition problem. can you help me thanks

Ya need to get it checked for codes,vacuum leaks,ignition wiring,cap, rotor,injectors,etc. I don't suggest driving it around too much with a flashing check engine light.

Thank you Delta i had a vacuum leak and it seems to be better. it is raining tonight so the test really comes when i try it. again thanks so much