+1 on the cables as all the signs are pointing to a power issue. The ECU hates fluctuations. If terminals are good I would follow the leads back to ensure you got a good ground to the chassi as well the + terminal cable is clean and tight both ends.
Only other thing I might look for and I'm not positive the Vegas V92is the same but on the right side of the TBs there might be two vacuum plugs that could be leaking air jacking up the idle causing your power flucs
Keep us posted
2011 White Vision - Nuvi 550, Lowers, Lloydz 2nd filter, Vic perf filter, CB/Icom, 96 Brake LED's, Clear Signal lens/Switchbacks, VIC Hwy Pegs, Stebel Horn, 7Jurock 15" Shield, PCV, Lloyd ATS and Variable intake, Ness honkers
2004 V92 TC - S1 flash, level 1 slip-on, Ness big sucker K&N, ISO Grips, 4x1.5 Highway Hawg Risers, extra chrome (never too much), JM 2k CB 4' antena, Mustang seat, HD Front TS & Lowers, OD Pulley
Retired Navy SCPO