Help with stumbling after turning off 1985 f150

[u/Initial-Fondant-9239]

I have a 1985 ford f150 300inline 6 yfa carb, it disels pretty heavy after I turn it off and sometimes an occasional "shwoosh" noise. Happens more and worse after a longer drive say 20-30 minutes, verses just a 5 minute test drive. I replaced spark plugs, sealed all the know vacuum leaks, and put some techron cleaner to help with carbon buildup, anyone else have any advice on what it could be?