R300 missfire & cutout today when hot

[navi]

Driving today it was pretty hot, my R300 K series (2003) cut out completely twice, pulled over, re-started both times OK, but then cut out a third time, and had to wait appx 10 mins before re-start. Temp gauge 80-85. Also, may be connected - previously when engine hot (80-85) when ticking over rev counter will dive down to 0 and the engine will miss a beat, then it will shoot back up and be fine????
This previously happened every 2-3 mins, but is now happening more frequently. Also when hot, if flooring it from tick-over, it splutters and then will pick up sometimes. Have a feeling its either a coil breaking down or a module.....If anyone has any ideas would be very grateful.

[ArosaMike]

Could be a coil, or also perhaps a bad earth/short. Check all the earth points for corrosion and then check the loom in areas that it might rub on bits of chassis for exposed wires. Might be worth getting someone to plug the ECU in as it should record fault.

[navi]

Just been to see a mate who reckons it could be one of the coils going down to earth, as we can feel it clicking in the ignition module. Tried to plug it in to a snap-on diagnostic box, but the box couldn't connect with the ECU.....is this because you need a special diagnostic box to access the ECU?

[Walton]

I had a similar problem at Bedford today.

Car seemed to hit a rev-limiter at 6000rpm, then it came down further to 5500rpm. After 20mins rest it was okay for a lap then happened again. I presumed it was ECU protection to prevent heat build-up.