Ford Repair: 1994 Bronco Transmission slippage, vehicle speed sensor, transmission slippage

Question
I have a 1994 Ford Bronco, 5.8L engine.  Recently the transmission has been "slipping" out while driving, usually around 40-45MPH while maintaining speed, not under acceleration.  Unfortunately, I am told the actual problem causing this is hard to diagnose until a part fails; the problem could be a speed sensor, throttle sensor, or the ECM.  My questions are:

1 - does this sound correct?
2 - is any one part known to be more likely than others?
3 - are these something a non-mechanic like myself can easily replace?

Thanks!
-Ed

Answer
Hello and thanks for the question...I'll try to help.
Sometimes failure is the best way to find out what's wrong or went wrong....but what they are saying doesnt sound correct.
A hook up of a scan tool would be able to tell any garage IF the VSS (vehicle speed sensor) is going out of renge, if the TPS is out, IF the ECM might be going bad.
I wouldn't go replacing any parts until you KNOW they are bad or have failed. It can get expensive in a hurry.
A pan drop of the transmission and an inspection would be a good place to start. See if there is any material in the pan and also note the condition of the fluid.
Erik