A4LD shift issue.

[90Aero]

I have a 90 Aerostar that while in D or OD will not shift from 1st to 2nd, but will manually shift. I put a new Vacuum diaphragm and no change. I checked the control pressure at idle and its high in all gears. According to the shop manual when the pressure is high at idle in all gears its one of these:
1. Vacuum diaphragm (New)
2. Vacuum diaphragm control rod (Looked great)
3. Manifold vacuum (Strong)
4. Sticking Regulator Boost Valves

It would seem to be the Boost Valve. Why would it stick? The Fluid is and always has been clean. Must I pull the valve body to get the boost valve out and if I do, will I need a replacement valve body gasket of some kind?
Also does this Boost valve make sense if it manually shifts?

(Oh, I should add that when it warms up, it does start to shift, but I hesitate to say it shifts normally. I would say its delayed)

 

[BrooklynBay]

Welcome to this forum! I've moved your post into its own thread in the Aerostar section. You might have a sticking governor or a broken band. Most likely it's the governor since the issue occurs while it's cold.

 

[90Aero]

Welcome to this forum! I've moved your post into its own thread in the Aerostar section. You might have a sticking governor or a broken band. Most likely it's the governor since the issue occurs while it's cold.

I have also read in a few spots that it might be the governor. The governor is apparently in the tail housing. Can that be accessed on the vehicle, or must the transmission be removed?

Is there any definitive test that I can try or actions I can take externally to get it working again?

 

[BrooklynBay]

You could remove the tail housing & driveshaft while the transmission is still in the vehicle. Check # 45 in my list of useful threads: http://www.explorerforum.com/forums/showthread.php?t=155582