1971 Mercury Montego Choke?

Most guys at auto parts store unless tehy were mechanics for a long time first really are taking an educated guess. You car has a choke and if your car has sat for a long time or ben dirven for the past few years there is alot of alcohol in the fuel that wasn't when your car was built. The alcohol is not the accelerator pump or power valves friend if it hasn't got a newer one in it. It could be the choke but if it was it would only act up when it was cold. As you haven't said when it acts up i'm thinking it's all the time. Of course your engine may be idling to low as well. Or an ignition problem. If it does it hot then it's probably the whole carb itself needing a rebuild. You should have apro look at it, at least somone who has worked on carbs in the past.