Motor was rebuilt about a month ago and ive managed to put about 50 miles on it but ive been having a reocuring problem that just doesnt want to go away. The car is a 10 AE . The motor is an s4 ported motor with S5 internals. The car turns on with no problems , idles fine and revs fine while in neutral but you put the car in first and try to take of it wants to die. I changed all the vacume lines, and upper and lower manifold gaskets to eliminate any posibility of vacume leaks and the problem didnt go away. Checked all the couplings on the intercooler piping and still nouthing. I had a mechanic friend of mine come by and check it out, he hooked a machine to check for codes and none popped up. We switched the Rtek chipped ecu out for one that wasnt chipped and nothing. We hooked up a wide band to it and the A/F at idle were almost 19 so we put up the fuel pressure up to about 55 psi and we got it to take off and the A/F at idle were staying at about 15 psi but once you got past 2500 rpm the A/F would drop to about low 10's. So he told me i might have a bad AFM and my primary injectors might be dirty. I took out all the injectors and had them cleaned. When i put them back on and dropped the Fuel pressure back down to about 35 psi the car was running ok But still felt kind of held up. The AFM i got from a forum member and i put it on yesterday morning and the car was still running the same OK but still kind of held up. Last night i went to take the car for a drive to try to get some miles on it and the problem started again. It turned on fine idled fine reved fine while in Neutral but when i went to take of it wanted to die. Can some one lead me in any direction that might help me solve this problem.

i put a wideband on mine too and it was happily running 18:1 afr at idle, the air pump throws off the readings....



things i'd check:



clutch switch, they do funky things, basically it tells the ecu you've got your foot on the clutch.



air control valve; these like to leak and just go bad, if your car is running really lean, it sounds like its working



vacuum lines; the routing is key, i had a crossed pair, and the car would flood hot. uncrossed em, and it would happily start hot....

When i put the vacume lines on i put them back the same way it was when it was running good before the motor blew and they are all new.



What and were is the clutch switch?



After i change the fuel filter ill check the Air Control Valve next.

clutch swith is up at the top of the clutch pedal. its just on off