When you clean the TBs, looking on the right side of the bodies you will see a vacuum port 1 in each body. Based on age could be dry rotted. Next is exhaust gasket at the cans. Hard brittle and leak. This could Also be cause of decel popping. I would at least check for exhaust leaks first. 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