Do I need a choke?

Absolutely zero. You need to DIAGNOSE the problem first. Fix it. Then throw money at it if you still want to. Throwing money at something FIRST rarely results in success.
And when you were selling parts, how many times did a customer bring back a carburetor or some electrical part complaining that it was faulty, and they wanted their money back. I worked ar a Western Auto for five years after I got out of the Air Force. Occasionally a customer would be honest and admit that the part just did not fix the problem. I would guess that 20% of the carburetors we sold came back.