Thanks for the reply. I'll take a look at a plug this weekend. Plugs and opti have about 20k on them. It may be worth noting that I have a newer set of wires on one side as I haven't had time to do the other side yet, although this happened before the new wires, it seems to be happening more often now. The passenger side wires have 20k on them, the driver's side maybe 200 miles. I found the number 5 plug had been pretty badly burned past the insulation and had split into the wire, it was actually running good, so i had no idea. I put an LT4 knock module in the car when the motor was at 12k. It occurs as far as I have noticed in closed loop and does it 2-3 times per drive, but not usually on short drives. Although not always on a hill, the type of acceleration it occurs in is just like the amount of gas you would give if you were going up a hill. It seems also that it happens when you're coasting and you give it the gas, like coming out of a turn and accelerating when it gets straight. The car has also always backfired/misfired in a pop sound in the front occasionally and I've never been able to figure out why. I also smell coolant often when I turn off my car or sometimes at a stop light but have never been able to find it, so could be waterpump weephole onto opti. Though I do have a cowl hood so I naturally would smell stuff more, even though I smell it the strongest right as I'm getting out the car.