It doesn't happen often but occasionally when I'm driving everything seems normal but when I left off the gas the engine will drag as if it's in a lower gear than it should be. When I press the gas again is when I notice that I'm not in the proper gear. When this happens, I can shift into neutral and back into drive and it will go back to normal. Is this a sign of worn fluid or do I need to be getting a transmission from the junkyard, have it rebuilt and hope this one doesn't go completely out before the other one is ready to put in?

(Signature is wrong and I don't feel like hunting down how to change it on my phone... So...)
'93 F-150 XLT
Regular Cab
Short/Regular Bed
4x4
V8 5.0 302

 

Is speedo working?

 

Is it throwing any codes? I don't think that's a sign of bad fluid..