Try disconnecting the FMU (I'm guessing a boost dependant one) and just run the OE FPR and see what happens (at least eliminate that as a cause). Maybe a compression test and double check everything in the ignition system (cap, rotor, plugs, wires). My coupe developed a miss and all my tools are over at the place I work under my clip. I finally got over there to figure out what it was and it turns out my plug wires were coming apart (tired to pull #1 and only got the top of the actual boot).
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Andy - Reinstated
Hybrid Forum Moderator
'06 Subaru Legacy Spec B - Stock, for now
'98 Civic EX - CTR headlights and grill, Kosei K1's, for sale
'90 240SX - SR20DET that will never get installed, project car.