Hello,
First time using and being a part of a forum!!

1999 Ford F150 4.2L V6. XLT automatic. a bit over 300,000 miles.

Issue: When I am on the freeway going about 50 mph everything seems fine. When I reach the 55 Mph mark or over, it seems like I have no power to pick up the speed and feels like it is not setting in to high gear. I tried fiddling with the overdrive button, which does nothing.

Diagnosis: Please share your input, and what I should I do?

Background Information: Father pass not to long ago, and was able to use the truck for a few days. I was told the truck leaks oil (saw a drip line from the rear main seal) , transmission leaks (around the trans pan) and the power steering leaks (one of the inline tube is loose from the pump). All of this has been leaking for quite a while. I figured the trans fluid was low enough to cause this issue. ** on top of that, a friend borrowed this truck 7 months ago and added Dexton/Murcon LV trans fluid**. Which this truck suppose to take Mercron V. Hope all goes well, I would like to have this truck around for another 5 years if possible.

Project List: Taking matter in my own hands and after doing intense research and reading forums.
1. Already taken out the transmission & torque converter, exhaust system (from the end of the manifold to the tail pipe) and the crossmember. I realized I still have the truck set in parking gear, and disconnected the Transmission shifter level would that be a problem?

2. Ordered items: Rear main seal, Torque converter Mid-stall, Power steering, Transmission mount -rubber, transmission oil pump seal (to replace before installing a new TC), thinking ordering passenger & driver side motor mount **a big lesson learn: When taking off your transmission, and letting the truck sit for a period of time -be sure to prop the rear engine up so it wont sag and cause the motor mount to tweak out. There is movement when I push on the bottom of the oil pan **.

I need help with Torque Specs:
Torque Converter to Flex plate nuts: 20 ft/lbs ??
Flex plate bolts to engine crankshaft: ? ? ? (need to remove to replace rear main seal)
Rear main plate/cover bolts to engine: 89 inch/lbs ?? (need to remove to replace rear main seal)
Transmission mount (higher - small part): 80 ft/lbs ??
Transmission mount (lower - longer part): 50 ft/lbs ??
Transmission bolts to Engine: 30 - 35 ft/lbs ??
Transmission cooler line to transmission: hand tight and 1/4" tighter ??
Transmission crossmember bar: 40 ft/lbs ??
Transmission Pan: 10 ft/lbs ??
Starter bolt to Transmission: 18 ft/lb ??
Rear Drive shaft bolts to axel: 90 ft/lbs ??
Exhaust bolts to the joint exhaust manifold: 30 ft/lbs ??
Driver side motor mount: ???
Passenger side motor mount: ???

Question to ponder on:
Will pour 2 quarts of transmission fluid in the torque converter before installing in the Transmission.
1. Looking at the Felt-pro Rear main seal, do I rub damp the seal - crankshaft side with transmission fluid? there is no instruction with the seal.
2. I realized I still have the truck set in parking gear, and disconnected the Transmission shifter level would that be a problem?
3. any advice?

Thank you