Tired of DIY!

Get that old gas out of there, modern ethanol-gas goes bad in a few months or less esp. in high heat if left vented to the open air and will definitely make it run like crap. FWIW when I overhauled the 318 in my Duster and incorrectly installed the replacement rear main seal it didn't leave much oil residue on the engine or bellhousing at all but whenever the car was driven and then parked there would be 5-10 oil drops that would accumulate right under the lowest part of the bellhousing. Also looking up between the crank and flex plate/back of the oil pan area I could see oil coming from that area. I finally got fed up with leaving oil puddles everywhere and replaced the rear main seal with the engine in the car, it wasn't too bad and if it's the newer hard rubber type they're pretty easy to push around the "back" side of the crankshaft to remove.

Wrenching in high heat does suck bigtime, depending on the humidity of your area (I know TX is generally pretty humid, it works better in dry air) try soaking a towel to hang around your neck and/or your shirt in water. And drink lots of ice-cold water, beer will just make your brain work even worse and sugary soda is bad for your health (and no diet soda isn't better), plus the frequent need to pee will force you to take breaks and go inside lol.