R129 320 V6 misfire

[Lastinclass]

I've got a problem with my 1999 V6 320 R129. Occassionally when I start it up it misfires badly like its on 3 cylinders, if I key off and start it again it's perfect. In addition just lately it won't take more than about 60% throttle without misfiring/feeling like TC cuts in. No MIL on and no TC light on. It does it sitting still, runs fine on light throttle but on heavy throttle it misfires... unless you press the brake then in runs like a dream!!!

Any ideas??

[Lastinclass]

Got to the bottom of the issue - air flow meter! New meter and running like a dream again..