Hi guys,

Got a friend with with a 3.0 TF which keeps stuttering.
It had oil in the plug tubes, so replaced the o-rings + new leads and new plugs. Went great for a week until on a 300km trip it started all over again.
The spark plug tubes are clean of any oil.
What could this be??
Car has 361K km

it could be the coil, the dizzy cap, rotor button, might have a little oil inside the dizzy (however this is not very common for the 3rd gen magnas) with the dizzy cap (distribitor) take it off, inspect for cracks, corrosion on the contacts, check the little center button in the middle of the cap, make sure it moves freely (its spring loaded). check the rotor button for burning at the tip, corrosion at the tip and also inside the contacts in the middle of the rotor button. check the plastic cover for cracks that seals the internals of the distribitor from the cap. finally, the coil could be at fault. that should be anough to keep you out of trouble for a little bit lol

When does it miss.
Idle, heavy acceleration, light acceleration, steady cruise, hot, cold, warm, all the time??
Gerry

It misses under load in a high gear (ie 3rd/4th) and at fairly low rpm, around the 2000 range. It doesn't miss at high rpm or 1st gear etc.

The weird thing is with new plugs leads it lasted for almost 1,000km running completely fine, then on a long trip it started again

Spetz,
Starts to narrow it down. If it was leads it would be worse under acceleration. There would likely be no problems at all under light loads.
No problem when high fuel delivery is required.
You are describing a situation where the ignition system isn't that heavily loaded.
My guess is maybe that some of the injectors are a bit blocked. I had a similar problem with a KS many years ago. Got the local injector cleaning place who was a couple of doors away to check and clean. Before there was a major difference between the best and worst injectors, 2 of them were flowing about 50%.
After a good ultrasonic clean you couldn't see any significant difference across all 6 injectors.
Felt like a rocket ship afterwards.
BTW this was caused by crap petrol form a private fuel pump where I worked at the time.
Gerry

Thanks Spud,

The only concern though is that once new plugs/leads were put in, the problem disappeared for 1,000km or so. Which I assume this would mean the problem is somewhere there?
If it helps, the car doesn't miss when cold, but after driving for 10mins it starts missing.
Is it possible oil is fouling the plugs in the combustion chamber?