99 Chevy Cavalier - Worth Saving?

Hey there. I just spent $650 for a repair on my Chevy Cavalier (replaced whatever outrageously expensive part sits just behind the gas tank.) Gotten the car back and it seemed to run fine until it sputtered and died after running a few miles and then idleing in rush hour traffic. My mechanic gave me the advice to turn the ingition on and off three times to get it to start and sure enough, it worked after a few minutes.

The car has 135K on it. I've gotten to this point before with my vehicles where it seems I pour about $1,500 into them before I decide it's just going to be one thing after another.

Any opinions on whether this is a simple fix or whether I should take it to the dealer (my mechanic is old school without a diagnostic computer in sight.)

Thanks fellas, your expertise is MUCH appreciated.