2001 Ford Escape stalling on idle, in park, putter

I have a 2001 Ford Escape V6 4WD 3.0. OK, i went out and warmed up my car, went back out 10 min later and it had stalled. It started right back up but ran crappy in park as if was “choking”, “puttering” and “jerking” and when i was reversing very slowly, and while i was going forward very slowly pulling out. Once i got going and all the way to 75mph it ran perfect. When i came to a stop light OR put it in park, it idled at 1000rpm for about 10 sec then the rpm dropped lower and lower until it stalled. It always starts right back up and then runs crappy in park or at a stop then runs fine again once i get going. Then the check engine light came on. I went to Autozone and had my codes read and got P0304 “misfire cylinder 4”. Since i already had my codes read i went and disconnected the battery cables to reset. Once reset i had the exact same issues but the check engine light has still not come back on and I’ve driven well over 150 miles. OK, i do smell burning oil “sometimes” however, when i got an oil change in 2012 they said my oil pan gasket had a very slight leak, I do hear a hissing “maybe a vacuum leak” toward the rear top of the engine, and to make things even worse, when i disconnected the coil on plug on cyl 4, 5, 6 i heard NO significant drop in idle for any of them really “i did this because the P0304 code. Any ideas? If you can help at all i would greatly appreciate it. I’m low on funds and by know means wealthy LOL so i need to fix it while spending as little cash as possible, so I’m trying to diagnose it myself before i go spending money.