My daughter found a 1970 Ranger XLT for my son. I have been fixing many small problems but one I cannot figure out: Starts fine, idles fine, starts in 2nd gear fine (1st is granny) but when shifting to third it misses and very rough. a little clutch and lots of gas the engine stabilizes and accelerates fine.
any ideas all you smart fellas?

 

Missing and roughness points towards misfiring. Hesitation, balking is carburation.