I'll let you know right now that blowers are not my strong point, and that Mike will probably be of more help than I will, but your last comment made me think. Did you clean your MAF? The only problem I am aware of with having a K&N mounted the way you do is that the probablity of oil getting from the filter to the MAF is pretty high, and an oily MAF wire will affect driveability. I am not familiar with your brand of MAF, though.
I am surprised that the car could experience such a severe drivability problem without the ECM noting anything. have you tried driving with the scanner hook up and monitored your system? I would like to know if the ECM concurs with your rich/lean indicator when this happens. The idea of bypassing the blower will tell you if it's blower related, so to "cut the pie in half", you might want to try that. It's solvable. Difficult, but solvable!
Take care
~Chris
------------------
Retired Moderator
MustangNet
My site:
JimPorterRacing
RACECAR spelled backwards is RACECAR
HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!