Certain domestic trucks will flood badly after you shock the carb with a hard hit - is there a chance that you're hitting these drifts hard enough that you're simply massively flooding the engine? I personally doubt this, but thought I'd put it out there. It's pretty hard to upset an OEM Aisin carb.
Steve H. - KE0KNH
Colo Springs, CO
'78 FJ40, '89 FJ62, '98 4Runner