FIXED - Fort wouldn't climb past 14,000

[Tailspin45]

I've flown A2A's incredible Fort to 34,000 in the past, and high 20s numerous times. But recently she won't go above about 14,500.

First symptom is gradual increase in right rudder starting at about 13,000, then slow decrease in CHT on #1 and #2. MP and RPM remain the same on all engines.

If I squeeze every ounce of lift out of the old girl I can drag her up to 14,500, even 15,000 if I hold my tongue just right. But then the RPM on the left side slowly starts to unwind, and it's apparent that #1 and #2 are packing up. But they never quite quit, more like malingering.

Tried removing the add-on ice gauge, no help. Tried all combinations of mixture, RPM, cowl flaps, intercooler, MP, throttle position, blower. No help. Tried uninstalling every file I could find after regular uninstall and reinstalling. No help

Then I tried looking at things with AFSD, and discovered the mixture on the two left engines is FUBAR and running very rich. Mixture controls match and all four engines fuel/air ration change but left ones remain very rich.

WAIT! Hmmm, what about FSUIPC. Stand by, I'm checking... Yup that was it. Mixture axis wasn't set to handle all 4 engines and left ones never leaned as we climbed. Not sure why MP didn't suffer. But problem solved.