Bill, allow me to jump in, if his problem is like mine, which it sounds like it is, I believe he is saying most of the time, when he starts the car, there is no sign of any problems. However, sometimes, completely at random, when the car is started, and put into gear, it will accelerate fine up to boost conditions but then runs horribly until he lifts off the pedal and reapplies the gas. Once again, when it hits boost or slightly after, the engine starts backfiring and looses power to the point of decelerating. If the car is shut off, and restarted, the problem vanishes until the next time it decides to pop up.