Hey guys my engine starts to lean out pretty bad after it's been running for about 2.5 tanks without shutting it down. It runs perfectly for two or three tanks, then temps start rising and engine starts lean stuttering and pitch changes (almost sounds like when you are about to run out of fuel) then finally dies. When this lean condition appears, richening the needles by a few hours is not enough to counteract it...

It shouldn't be an air leak as this is a new engine with about a gallon through it, and an air leak would cause more erratic behavior throughout the entire run.

Pressure line? Fuel filter? What should I look for? Followed the typical GO run-in procedure exactly.