Help with engine problems suggestions

Hey everyone, I have a 2005 4.0l 1 of 1 mustang, it is a one of one because it is the first and only 4.0l 6spd/Auto with a Vortech Supercharger. I currently have issues as such; cracked valve covers at the bolt holes and I got ripped off but “liquid gaskets” when I needed new valve cover gaskets, this is the second engine. Only because the original owner took it to jiffy lube for a oil change and they hand tightened the oil pan nut and it popped out while driving and seized the engine, I believe they dropped this engine in without a tune so my A/F is completely wrong bouncing from 7.5 to max of - - I also replaced the intake filter which helped the A/F ratio a little bit to where now it doesn’t top out in an idle but a very rough idle. It’ll stall when you shift to a “moving” gear such as R,D,1,2,3. I currently haven’t started in months but I have it connected to a long term battery charger so it won’t die completely. I need peoples opinions what I should do, I get $965/month cause I’m on disability, I thought repairing everything and get a tune, my best quote in the state of Washington was $1200 for the valve covers and gaskets and $2000 for a full custom tune because “they didn’t know how bad the tune was and what they had to do”. Now, that’s not in my budget so I thought why not engine swap. I was looking for another 4.0 but not much room for improvement, so I then thought if I upgrade I can’t do a V8 otherwise it’ll lose the 1 of 1 plague, so I’d have to do a V6 or V10 but doing research on a mustang with a 6.7 f250 engine and everyone said it would ruin the ride because of the weight. I’m personally out of ideas so I’m leaving this with you for y’all’s help and opinions, pls/ty guys ✌🏻 Also here’s a couple photos for y’all too..