i am having problums with my 1994 E 350 motor home it seems to stall or miss when driving we changed the throttle controle sensor and it did not help so we took it to the dealer for a diagonostic scan when he hooked it up he says his scaner went haywire and gave him false reedings??????? he coulden understand...??? some how he to came to the conclusion that the throttle controle sensor was sending false signals to the trottle control valve ???/ he replaced the sensor and the valve both and thay went out as soon as he did that...same problum as before... now he says he is stumped and wants me to tow it away !!!!!! ... Now we have dealer and diagnosis problums... hope fully some one out there may have had a simmler problum and can help me .i dont know were to turn ... i allways thought the ford dealer could fix any thing on my ford cars and trucks maybe i was ronge about that !!!! if the dealer cant fix it who can ????????????????

changing the throttle control sensor had no effect?
I guess you didn't get any codes from the dealer? Try AutoZone or Checker, they'll read it for free.

I would have looked at the plugs first, look in the throttle body for build-up. There are a lot of things that could cause this.

What size engine? Mileage?

It seems to me that the dealer was completely wrong about these. You said the problem was when you are driving, the trottle control valve is for idling control only. As for not being able to use a scan tool on the vehicle, it might have been he's scan tool or the RV's computer. I'm thinking its one of the O2 sensor, but I wouldn't change anything until its bean diagnostis. Try calling some RV centers around you, or maybe try a different Ford dealer. GOOD LUCK