Automatic trans question

[old school truck dude]

90 GMC 1/2 ton 4x4 -

Starts off in 1st, winds up pretty high then shifts hard into 2nd, will not shift into 3rd or od, shifts into nuetral if you let off the gas. This goes on for approximately 10 minutes when cold, then all of a sudden its just fine and behaves normally. Whats wrong with this thing?

[J.C.]

Check fluid level?

[old school truck dude]

Clean and full

[lilred]

Any chance there is water in it? sounds like something is frozen in the valve body

[old school truck dude]

Doubt it, it did the same thing back in August of 2012 when I had it running the last time.. But it's very possible that it has water in it as I swamped it at the Sears bog when it was in the gray truck.. Fluid looks real good in it, though..

[lilred]

Just a thought. Dunno. Most of my stuff has 3 pedals