Vw polo 2005 no power, no diag code?

I have a 2005, VW Polo 1.6. Afer start up it has no power at all, almost like too much fuel and no air / bad timing symptoms. 3 different scanners show no fault, have changed fuel pump (original), coils, crankshaft speed sensor, checked timing belt, tried 2nd hand EGR valve etct etc - driving me absolutely crazy. Has any one had similar problem or know which way to go next? ECU?
Any help welcome!

RJA
July 2009