I was reading thru some of the posts and was wondering if the 91 F-150 4WD with a E4OD has a thermistor that would that would make it lunge when you take (after it warms up from a starting stop you have to rev it up little to get it to go)

 

I have no idea what a thermistor is.

When was the last tune-up including all filters and PCV valve? How many miles are on it? Is the check engine or O/D light blinking?

 

Thermistor - Wikipedia, the free encyclopedia For Andym.
Not sure I understand your post but a clogged trans filter may be one answer to it.

 

Learn something every day. I know the E4OD does have a trans oil temperature sender but as far as I know it's just to let the computer know the oil temp is too high.

Since we don't know whether the transmission or engine is causing the problem I'd hate to start recommending specific services to check/perform.

 

[quote=andym;11466994]Learn something every day.
Isn`t that the truth.

 

I learn something every day... problem is I seem to forget several things every day also. By the time I'm 60 I'll be lucky to be able to tie my shoes at this rate!

OP, you say you have to rev it up to get it moving. How much are you talking about? The first things to check are level and condition of the transmission fluid.

 

This sounds like a low pressure situation. When it is cold, the oil in the trans is thicker so it has enough pressure to keep the clutch pack engaged. When the oil heats up and gets thinner, the pressure is low enough that you are essentially dropping into neutral at idle. So you have to rev it up to raise the line pressure in the trans high enough to re-engage drive.

My '71 GTO in high school did the exact same thing - it was the pump in the trans that was bad. I drove it that way for about a year before I could afford to get it fixed - I just had to be gentle with acceleration from a stop.