My 2000 Pontiac Grand Prix has the following problems. I will be driving and the tachometer will drop to zero and the car will jerk but still run. Now I am also having problems with the car shutting off but it usually restarts and the tach will work after restarting too. It seems to be a worse problem when its extremely hot. Sometime the car won't start and sometimes it will run but shut down and the exhaust stinks like it is real lean. The other day it would not start and i checked it had no spark so I changed the control module and it seemed to be okay for a couple of weeks. Now it is doing it again. Does anyone have ideas or had the same problem? Would a crank sensor cause this? And what symptoms would a bad cam sensor give me. There are no codes being thrown off by the computer. Any ideas or help would be appreciated