Ebay GT45 + 5.9 Magnum + E85 blow thru
On a gut feeling I checked the distributor. The phasable rotor was lose AND the distro hold down was loose. I think the whole thing got shook into a too advanced position. I reset everything and put the timing light on it to get the timing squared away. It's much better now (not 100%,) but I still need to recheck rotor phase and probably reset IAC setting on the Fitech.