Is it the motor or???
 

I have a 2003 G35 and I love car BUT I may have to get rid of it because of issues that I am not sure if they can be resolved. 1 - When I go to crank my car, sometimes it takes a minute for it to crank (I believe it is one of the Cam Shaft Sensors?). It even cuts off if I downshifting to come to a stop or slow down. :( 2 - Also, I experience a LOUD squealing sound once I get it cranked. I believe this is slack in a belt. 3 - My car is making a loud muffler noise as well. I don't believe it's the muffler because once the engine warms up, I don't hear it as much. Any suggestions as to what some of the issues are with my car AND how to go about repairing them? I'm at my last wits with this car even though I really love it. :confused2::dunno:

Take it to a local independent shop. Most places will diagnose for free and you can choose how to move on from there, also be sure to pull codes from the cars computer or check if any are stored, as they'll help pinpoint what's going wrong