I have a 1966 C20B (Ser.# C20B 604 2054) that has run without issue for the last 15 years (that I've had it). Suddenly the other day, it wouldn't stay running...aka won't idle. It starts up no problem, and runs fine if given gas, but as soon as you let off the throttle it sputters out.
One thing led to another and we've done a pretty complete general maintenance update, as most components seemed virtually original. New hoses, filters, vaporizer and solenoid, plugs and wires, cap and rotor, coil, cables and rebuilt generator.

I'm wondering if maybe it's something electrical? The wiring has always been pretty wonky in this thing...in the sense that people have spliced and taped and pulled things out over the years it appears. But, as it's never had an issue, we've never bothered touching that aspect. I wonder now if something finally gave way perhaps.
I see all the old Clark manuals on their website, but they don't appear to have wiring diagrams in them.

I'm not that familiar with LP forklift mechanics, as I've been really lucky that this workhorse has never failed me in the least. Guess my luck has run out! Any clues would be appreciated.