Wont go into gear.

[RedGrizz]

Im hoping an Allison tech can help me out on this. 2005 Workhorse W-20 8.1 with Allison 5 speed.
Here is my issue. Everything has been fine until this winter when I went out to move the coach and it would not go into any gear. After about 3-4 min. it went in. Later if it sat for a few days it would again take a while to engage. trans warning lamps came on. Today I went to move it from a campsite and it took nearly 10 min. to engage and when it did the unit went in and out of gear several times before actually engaging. Temp was not really cold out. The unit was then in limp mode and started out in a higher gear so I shut it off and it reset then worked perfectly all the way home. (40) miles. It acts like the pump is loosing prime after sitting just a couple days. We were to leave on a 2000 mile trip in two days
Any help would be appreciated greatly. I can retreive codes for addl info if needed.
Thanks
RG

[OneRVer]

Don't know if this is any help,,,,but,,,,when was the last time you change your filters? Just a thought.