The transmision wont shift into 3rd when it gets warm but sometimes runs fine on highway but i come to a stop and it wont shift out of 2ed but if i shut off untill completly cool it will work again i already changed filter/fluid this is about my 97 ford windstar van

Drive it slowly to a reputable transmission shop. There is nothing you can fix yourself.

change trans oil and new filter if problem still there it most lickely the shift modual

If it wont shift at all, its very likely computer related. Its unlikely it could be vacuum because of its age. Their is a computer for newer trans and sometimes some of the components can fail. I once bought an accord that lost 2nd and 3rd due to its computer, shifted great after i hit the junk yard. If it shifts hard though, solenoids and valve body gasket.

Change the fluid and filter. If i remember correctly reverse and third gear share the same band and clutch pack. Some transmissions you could tighten the band on it.

You can not have vacuum leaks in exhaust,
before the converter.
It will effect the O2 Sensor,thus injector pulse

try moving the shifter to first and then second gear, until you get to drive. if one fails to switch then it can be a transmision problem. when that happens also try shutting of the car and restarting it and see if it continues to do the same thing. this might be because the trans is warm and does not shift properly, also the result being you need a knew trasnmision.

Change shift control sensor, or modulater valve, what ever you want to call it.

the solenoids are attached to the valve body. you nust remove the side cover to replace the solenoids. Your problem is probably burt clutches in the third clutch When you changed the oil was it black? this is an indication of burt clutches. only repair would be to replace the transmission.

I have a 2002 Hyundai Sonata and I had the same problem. But mine would always shift into 3rd gear and STAY there until I turned the car off. I took it to a Hyundai dealer and he had to rewire a speed sensor on top of the transmission. Apparently a little animal got up in that tight little spot and gnawed on my sensor wires. The car has run fine since. To make a long story short, it might be your speed sensor on your transmission.

The transmission/computer is designed not to go into overdrive until it reaches a certain temp and I don't remember what the temp is. Mine does same thing and it has 250,000 miles on it. When you start your truck up do you start it and warm up in neutral? The transmission fluid won't flow unless it is. There is know way to force it to shift into overdrive until it warms to the set temp.

Hope this helps
Howard