delayed engage

This could be caused by three things.

The first could be a torque converter problem. It may be that the that something is causing the flow from the converter to the impeller to miss by just a bit. The problem could be a vane on the converter or on the impeller.

The second could be a problem with the bands/clutches. If the bands are slipping slightly then it is possible that your transmission could be delayed going into drive. It could be the clutches or the bands. Usually, they break down in pairs so that if one goes then the other is sure to follow. So, if clutches or bands are slipping, then, your pickup will have a slipping upshift and delay.

Finally — and the one thing that I think is probably the issue causing the problem — your transmission fluid could be low. If the fluid is down by a quart or so, it means that the components in the transmission are working harder to get the proper pressure to have things work properly.

I think that if you check the fluid you will find it down. I’d suggest obtaining a quart or so to replace whatever may be missing and carefully adding it to refill things. I think that once you’ve refilled things, you’ll find the problem is fixed.

One other place to look is the filter. It could be that the transmission filter is plugged or nearly plugged and is slowing things up. To replace it, you’ll have to drain the fluid from the case, drop the pan cover (be sure there’s a bucket underneath to catch the quart of so of fluid that never gets drained properly), locate and replace the filter (and screen, too, if it needs it).