The quality of your gas wouldn't cause this problem. If it were, you'd have problems all the time, not just when hot.
Also, don't bother with the "Lucus" additives. That's snake oil in a bottle. So long as you use good gas, and change your fuel filter when necessary, you'll never need a gas additive.
Now as for you issue, when you say you changed the "Coil overs" for those cylinders, are you saying you installed new "Coils" for those cylinders? If you've done this already, then I suggest testing both the crankshaft position sensor and the camshaft position sensor.
You'll need to be handy with a DVOM to do this. And I recommend purchasing a "Single vehicle" subscription to a data service such as AllData or Mitchell 1. This will provide you with not only the procedures but illustrations and specifications as well. And it'll come in handy on your next project.
If your CKP and CMP check out, then you could do a pressure test on your fuel system. If you are getting "Multiple misfires", and you've isolated the ignitions system as a possible cause, I'd think your's would be an electrical problem since it occurs only when hot.
So when your engine is hot and your are experiencing this problem, listen to your fuel injectors with a stethoscope to see that they're firing at this time. If they are, proceed with a pressure test, both static and operating.
Compare your readings to spec. If your static pressure is out of spec, suspect the fuel pump. If your operating pressure is out of spec, suspect your fuel filter or injectors.
Tuesday, April 27th, 2010 AT 10:30 PM