Our son has 2001 Ford Ranger. We bought second hand and have maintained it extremely well over the past... 6 years we have owned. When started and engine is cold the rpm's rev up but the transmission is slow to shift... doesn't sound good. Taking to mechanic tomorrow but trying to get some info ahead of time.

Try dropping and cleaning the transmission pan, changing the filter, and refilling with Mobil 1 Synthetic Multi-Vehicle ATF. Ford recommends doing this every 30,000 miles. If this doesn't solve the problem, the clutch packs are likely shot.

The implication, imthatguy, is that if the fluid and filter have not been changed regularly, it has caused something fundamentally to go wrong. What's more likely, at that point, than slow shifting and worn clutch packs, particularly in first and second gear? Maybe the member will report back and tell us what the mechanic found out. Not a big jump at all.

I can't deny your theory is sound. But there are a few more things I would suspect before the clutch packs. That is all I was implying. Perhaps low line pressure(weak pump). Torque converter issue.

My real point, to carowner, was that if he dropped and cleaned the pan, changed the filter, and refilled with full synthetic AFT, which shifts much better in cold weather, then he needed a professional to check it out if it didn't solve the problem. After this, he would have done everything he could really do. The cause of low line pressure, weak pump, and worn clutch packs is usually the same--not changing the ATF and filter regularly. Poor maintenace results in varnish and sludge, low line pressures, worn pumps, worn clutches, slow shifting, and, ultimately, ATX failure. Pretty straight-forward stuff. Problems frequently manifest themselves in clutch pack failure (slipping), since they are last on the fluid line and the first to go.