Okay so, im not sure if my tranny is going out or its something else... 3.0 Auto 2005 140k miles
so the issue only happens when i dont drive my truck for about 8 hours, I start it up, give it a minute or two, and i out it in reverse and it goes straight into gear, then i put it in drive and sometimes ( not every time maybe 30% of the time ) it just soesnt go all the way into gear, like id let off the brakes and i would be creeping forawrd slowly but when i give it gas nothing happens, so i wait till it engages (it can take up to 20 seconds ) then its fine, it shifts good, but sometimes itll go and fall back out of gear and free rev (I ALWAYS let off the gas so it doesnt slam into gear) but this ONLY happens in the first couple minutes of driving after it was parked all day.

thoughts? Shift solenoid? I dont know anything about transmissions.

also note: i dropped the tranny pan and changed the filter and fluid ( didnt do a flush)

 

What if you shift it to 1st?
Does it engage right away