Vacuum leak, such as from a bad IMG, would not manifest symptoms until closed loop operation. In open loop the computer runs off of a pre program, ignoring input from sensors.
95 Trooper LS - 4" lift, 35" tires, 5.38 gears, ARB lockers
Indy4x Revolution 3.07:1 low range gears, Indy4x HD tie rods, homemade sway bar disconnects, Calmini HD sway bars, Darlington diff drop, OME 929 + 1" poly spacers and 1" body lift, Indy4x HD torsion bars, Indy4x HD rear axle links, Indy4x Kevlar brake lines, ARB bullbar, custom rear bumper, sliders, Optima yellow top, ARB mini-compressor, Indy4x kevlar air lines, Warn M8000 winch, Blue Sea 6006 winch cutoff switch, Yaesu FT-1900R 2-meter ham radio, Comet SS-680SB 1/2 wave antenna, Cobra 18WXST CB radio, Firestik II antenna, generic 8" driving lights, even more generic fog lights, and Dave's custom 1" shifter extension
"Speed has never killed anyone. Suddenly becoming stationary, that's what gets you." - Jeremy Clarkson