Problem only when cold so idle valve may be at fault i.e. not opening but if the AFM is ok then the ECU should deliver the correct fuel ratio to the recorded air flow.

Swapping the ECU seems the best thing to do now ,a good route foward I would suggest- should only take about 1 hr.

Bets of luck, let us know what happens.

Cheers

Ian

Well, car acted up again with the swapped AFM, so that's not the problem. Here's a real clear description of what it did: I'm in 1st, apply throttle, car acts like it is pulling a 2 ton weight, RPMS go up but reluctantly and car just doesn't want to go. I keep it 4000 rpms, car goes but again, I can feel I have a lot more throttle applied than I normally would to drive at a constant 4000 in 1st. Suddenly, after 20 secs or so, rpms zoom up past 5000 and car of course accelerates (without me moving the throttle - in fact I almost have to back off on throttle lest it redline). I shift to 2nd, and boom there is a small backfire when throttle released during shift. Then it drives fine. This ONLY happens when engine is stone cold and I drive away immediately. It also seems to only happen when the air temperature is say 45-70 degrees??!!? SO seems temp dependant, but I've put in a new coolant temp sensor, and swapped an AFM, which of course has the air temp sensor.
I have also checked the coolant temp sensor at the ECU plug, seems fine.

This is driving me nuts, my mechanic is baffled. Still offering a beer shipment (your choice) to anyone who hits upon a possible cause that I haven't tried...