Ferrari mondial 3 litre qv misfire

Sounds like fuel starvation to me, have you checked the filters? The new E10 car rot the rubber fuel hoses, parts of fuel pumps etc. in older cars.

 

when you drian it, tip the contents into a jam jar/ glass to see if there is any rubber bits in it. If there is you will have to clean tanks, blow out fuel lines have injectors cleaned etc, I had a 456 that did this and it was the rubber that held the pumps into the tanks that had perished and filled up the system!
I hope it is not this for your sake.

 

Hi Gary, Years ago, I had no end of problems with my old 1983 Mondial QV. From an ignition POV I had discovered the "ballast resistors" that are in line with the spark plugs (pink in colour?) could go open circuit or high resistance when measured with a hand held DMM they should all be roughly the same resistance. This had the effect of weakening the spark and causing rough running and misfire. I replaced all 8 in my car, fixed that problem. I also had one whole cylinder bank go down but that was traced to an open circuir flywheel sensor at the 11 o'clock position when you look through the wheel arch from the clutch (LHS). Got this done at the garage as the sensor was well stuck in the bell housing so not a home fix in my case once sorted the car ran well. From a fuel POV I had a faulty fuel accumulator which caused very poor hot starting but in general once replaced I found the mechanical fuel injection system pretty bomb proof in the 14 years of my ownership.
Cheers,
Mario