Holden Commodore 1997 Problems

It's the old story; it's either a problem on the fuel side or one of the spark side. My inclination is to check the fuel pump, Commodores had problems with the in-tank pump, and I'm thinking it's not supplying the fuel.

Intermittent problems are always difficult to find if they don't occur when the mechanic is there to witness it, but I would be looking at an engine sensor, crank angle or O2, as the most likely cause.

It's odd that these problems should start after you had the new radiator fitted. I would suspect that whoever did the work did it poorly. Take it to an air-conditioning specialist.

Many thousands of V6 Commodores have been successfully converted and there’s no reason to be afraid of converting your car. It would be fitted with an old style of system rather a new injection type, but there’s nothing wrong with that. A word of caution, however, is that you should make sure your engine is good and healthy before you convert it. It’s an old engine and I’m guessing it’s done lots of kays, so it’s worth having it thoroughly checked for tune and compression before you commit to the conversion.

Holden’s own recommendation is that E10 is fine for your model. There’s no reason to believe E10 would damage your engine.

The fact that it’s running roughly once it’s warmed up suggests you have a problem with either the head gasket or the head, even though there’s apparently no oil in the coolant. Try and identify which cylinder, or cylinders, are misfiring and remove that head to check it.