I have a stock 1991 FLT. When under load (like pulling a hill riding two up) I get bad exhaust fumes from exhaust. I rebuilt carb a year ago and at that time no fumes. Recently took carb back apart and float level was slightly high and I adjusted it to specs. This bike has 72,000 miles and this just started in last 1,000 miles. I cannot not see any holes in the rubber diapham for the slide. Changed plugs several tiimes and new air filter. Bike runs great. What in the carb could be worn to allow two much gas or too little air at 2,000-3,000 rpm just when pulling hard (on hill mainly). Could a weak coil or weak coil wire do this. I have not tested the coil. Any help appreciated, Thanks!!