Well i just recently installed a deck and now the car has trouble starting after leaving it overnight or for long periods of time. The first time starting it wouldnt work but then after that it starts up fine. its might be the wiring but not sure

 

Check your wiring. If you are having issues, more than likely you EITHER used crappy butt connectors or just taped the wires together. GHETTO methods lead to other problems.

 

as long as the wires are connected to the correct ones, shouldn't be having those problems.

does your head unit stay on after you turned the car off? what was the quality of the install? did you use an interconnect harness? or just hack the oem and twist up wire colors your best friend told you were right?