I have a 90 xlt lariat 4x4 with an aod transmission. What normally happens is I back out of the driveway in reverse then I'll put the the truck in drive and make it a mile down the road. I get to the first stop sign and when I try to proceed forward the truck won't move. I'll then wait a few seconds, usually less than 30, and then the transmission will engage. Once the truck is warm the problem seems to go away. I should note that the window for the gear selector doesn't always match up. Don't know how that would affect it.

 

so i've been wondering if a fluid and filter change would help. My buddy said he would advise against it. Saying that if I am having an issue it my be better just leaving it the way it is and getting as many miles out of it as I can. Any thoughts?