Hi,I have an '01 A6 Quattro with a 2.7 twin turbo.At times the engine runs poorly and power is low and at times the transmission bangs,other times it seems to run fine.Also at times when cruising/accelerating the traction control and ABS lights come on for a short period.It has codes P1555 max. boost pressure exceeded,PO103 MAF sensor signal too high and P1857 (trans. and ABS) Load signal error message from ECU intermittent.Has anyone had similar problems? Thanks very much for any suggestions.