When I had about 10,000 miles on my 02 Ranger, it had a symptom that the dealer diagnosed as a stretched and skipping chain. They replaced the chain at the direction of Ford to try to keep the cost of warranty repair down. I didn't agree with it but had no strong evidence to support my objection.
When the dealer was finished with it and said it was good to go, I took it for a test drive and it had the same jerky symptoms. I took it right back to the dealer and told them to save themselves, Ford and me more hassle in dealing with this issue and put a new transfer case in it (as they should have in the first place). I ended up getting what I wanted but I never did find out what was wrong with it, but it was not a skipping chain.
I have been told that chain skipping can be an issue with Rangers due to them getting stretched too much. I am pretty sure there is not adjustment. However, you may have another issue like I did.
2002 FX4 Bright Red Supercab 4.0 SOHC, manual 5-spd & Tcase, 33" BFG MTs, K&N air filter, Modified air box inlet, Gibson SS cat. back exhaust, Bama flash, Hidden Hitch round receiver, Rear helper air springs, Electric trailer brake controller, Line-X bed liner, WAAG bar with KC lights and Wildernest shell.