O/D light flashing causeing my transmission to not always shift on 1999 Ford Explorer

i have a 1999 ford explorer sport,4.0 6cly enginge SOHC 2W drive about 3 weeks ago, my vehicle was driveing well. then one day my O/D light started flashing. about 2 gours later it wouldnt go into gear, can some please tell me what could be causeing it and how it can be fixed.. when it is cold it goes into gear. when warm i lose pressure. please help me.

Asked by for the 1999 Ford Explorer
I drive an 2002 Explorer with 168,000 miles; it has the 5R55W automatic transmission in it. Like many of you, my O/D light started flashing, and I was getting a hard shift from 2-3. After much research , including from this site, I learned that the problem is NOT solved by replacing the transmission. The problem is solved by replacing the auto trans solenoid pack (drop the pan, replace the solenoid pack, replace the the pan and refill with fluid). I had the repair done for just over $500 - labor & parts. The challenge is finding a transmisson specialist who understands the problem and is willing to do the solenoid replacement INSTEAD of replacing the transmission. My transmission is now shifting silky smooth.
I was thinking of using Lucas Transmission Fix for this problem. Anyone try this?
1 more answer
When the O/D light is flashing, it is indicating that the transmission control module has detected a fault in the Transmission, or the electronic control system.
The next step is to retrieve the diagnostic trouble codes that are stored in the transmission control module and diagnose them accordingly. This may be best left to a transmission repair shop, I would look for an ATRA shop: http://bit.ly/ATRA_Info
If you do get the codes, post them here and we can give you some more info.
Good Luck!