I have a 2003 Pontiac Sunfire. I just recently had to put my car in the shop for repair due to the car will crank but not start. What I mean is the car's engine makes its normal sounds but it will not fire completely up. Since my local mechanic has had my car he has checked the battery it was good, checked my timing chain it was good, checked my starter it was good, checked my spark plugs they were good, checked my fuel pump it was good and my exhaust was good. My mechanic is running out of options does anyone know what could be going on?

Test for spark, could be bad ignition module.
Also a friends wouldnt start, ended up being plugged catalytic converter. unbolt the front pipe to manifold and see if it starts.