90Tazfreak

I have a 90 Toyota 2wd pickup that when the rpm is brought up to 2200 it floats between 2000-2200 rpm ! I've checked the timing , fuel level , and all vacuum lines but can't fix my problem ! Looking for suggestions ? It is a 5 speed , regular cab , short wheelbase , with 482000 km's on the clock ! The only other thing that I can think of is that the throttle shaft is worn enough that it is allowing air to enter when the throttle is moved off idle , but I don't have the time to yank the carb off right now !