I have a AFB 4055 (off 340) on my 300. The timing is set at 2.5 degrees at idle with vacuum disconnected. Newer distributor advance canister Pulls about 14" of semi steady vacuum New (today) accelerator pump piston Problems: won't idle below 1000 dies when put in gear backfires (with fire) when floored in neutral Due to life and medical problems, car hasn't been driven in about eight months, and was running ok before. I know the backfire is indicative of timing, right? Replaced accelerator pump as it was bad. I haven't hooked up the dwell meter to really get into the timing yet. Could this thing have jumped timing somehow? As always, thanks for any input.