Soft misfires and then a surge in power

[ken0204]

Hi ,

On my 1990 CQ20v I have a misfire and bogging down at 4000 rpm then another about 5000rpm. Then the engine goes ballistic to the redline like it should. The misfire and hesitancy is soft ( maybe the ecu clipping the ignition?) not hard like a cutting out of the ignition system which would have the engine leaping off its mounts.

It only happens under load whilst driving and not sitting still with me pulling the throttle cable under the bonnet.

Engine does not get that hot according to the temp gauge- 90-95 degrees and the oil only gets to 70-75 degrees . But every time I stop the engine the fans go on to cool the rad.

Got a bit of white smoke out the back on hard revving but head gasket seems ok using a chemical tester on the coolant

So which do I tackle in which order as these 7A engines are new to me!

- knock sensors
- lazy injector
- MAF
- throttle potentiometer
- anything else?

Thanks folks