The first thing I'd look at is your low speed needle setting. If its really rich that could do it. The way to check your low speed needle is to squeeze the fuel line shut while your car is idling and check how many seconds before your engine begins to speed up and then starts to die. Ideally, this should be 3-4 seconds. If less than 3, your setting is too lean. Open your needle up 1/4 turn and try again. If more than 4-5 seconds, your needle is too rich. Turn it in 1/4 turn and try again. Keep this up until you're in the 3-4 second range.