I have a 1993 F150 xlt. Its a 4x4 with a 300i6 and a auto trans. Ok. It misses only when its idling in park. It doesnt miss will driving or sitting still in drive with the brake applied. Only in park running. Oh and Ive noticed it either pings or clanks (however you wanna describe it lol) when in a bind like going uphill or pulling a load. I cant seem to figure it out. Thank you for any advice in advance.☺

 

sounds like the engine likes a little load on it, but too much and it pings. I would guess it's some kind of mixture issue, either vacuum leak or poor fuel pressure. start checking all your vac lines for cracks and get a pressure test on your fuel pump

 

I've heard of pinging and most guys would have the pinging issue if their timing was set to high. Try checking that with a timing light I think it should be around 10. Don't quote me on that though