2001 Saturn L300 Takes forever to start

Mechanic isn't sure, computer says it is misfiring. Sometimes it will start 2nd or 3rd try sometimes 30 minutes trying. The part(throttle actuator control module he would like to try is $500 for part only and he isn't positive that is it. "They are stumped". We have done all the maintenance that was suggested and the car has run very well for 10 years. I searched the internet and there are alot of unhappy people out there with this particular car and having many more problems. I was hoping to get a couple more years out of it. Please help. Thank you