I have a 94 eclipse gs, and i just replaced the head gasket, timing belt, and head bolts on it but now it hesitates when i try to start and after i drive it for more than ten minutes it takes about 10-20 seconds of holding the key down to get it started again. I think i might have a valve problem but i am not sure.

Did you check your timing?

yes, i had to do the timing a couple times but i finally got it perfect.

make sure its nothing stupid like a low power battery or ur starter...had that problem with my 98 talon a lot because the battery sux