i had the motor rebuilt, drove it 3 weeks and she crapped out, when it was rolling over all it would do is back fire soo i ordered a new cap and rotor (opti was brand new before it blew up the 1st time) and while its in i had my guy toss in my upgraded valve train and the 847 hopefully the opti does the trick!! if not back to the drawing board. but my mechanic is only charging me 250.00 in labor!! i about crapped my self when he said 250 i figured 5-700 maybe more!! but he is a great mechanic ive had good luck with him with previous cars so i have faith. but with the back fireing is the opti a possible culprit? what else could it be?