okay I recently purchased a 1994 ford mustang gtvert 5speedwith a powerdyne supercharger kit and a good tune gears etc. no built motor, it is all stock. So we put an offroad hpipe on it the wouldnt fit and put the highflow cat hpipe back on it. the problem was i drove it around a while with the o2 sensor on the drivers side(precat) hanging down not in the pipe hole and it took some hard bumps. Now I replaced that o2 sensor. but i still have this problem when i start it up it has a rough idle and then stalls unless you keep giving it throttle, and the throttle almost seems like its stuttering with when you push the gas and motor revs. Once it warms up its okay idling not perfect but still will stall once in awhile. It also flashes the check engine light off and on. What could be the first guess? i dont mind throwing parts at it. and i know i have to pull the code but i would like to save the time of getting a scanner etc. thanks for all the help!