'74 sticking throttle

I'm just getting my car legal again. I haven't driven it much in the last 1 1/2 years that I've had it. Mostly replacing faulty parts. My problem being, when I let off the gas, the throttle sticks, usually around 1500-2000RPM's. Not that big of a deal to hit the gas after I push in the clutch to bring it back down to 750, but why is it doing it. It has the original daul flat tops. I've tried some lube1 on the linkage, but it still does it. Any suggestions? I plan to replace the carbs later, but not right now. THanks everyone in advance.