i have just done a frame swap where i left all the running gear and engine loom on the frame while i lifted up the body and did the swap---i had driven the donor unit for quite sometime and all was well---after the swap i noticed when OD was applied i would get a fluttering feel like fuel was lacking----did the diagnostic--showed low voltage and purge valve not grounded----swapped in the purge valve----diagnostic is clean---same effect---swapped the vehicle computers (both 2000 auto 2wd) same fluttering--diagnostic still clean------color me baffled....bob