my \94 jetta is having trouble starting?

i have a 1994 jetta CL 2.0l, and it has trouble starting sometimes. I park it underground where not to many elements can get to it, but when i park it at work and its raining it has alot of trouble starting. It also has trouble starting when it's a little cold in the mourning, and when it does start it will sometimes almost bogg out when its stopped at a light or changing gears,but when its warm out in the mournig it starts fine. Could you help me fix the problem?