I've read thru what everyone has said about your issues with your truck. These individuals who know these older 4.0 engines have more experience than I do. Im more of a 3.0 owner.
I can provide some advice on the starter. I owned a 1994 ford ranger 3.0 5spd for 31 years until it was totaled last summer..not my fault. Thru the years I've always used motorcraft starters..better quality. As the decades went on, ford starters became to expensive. I checked with junkyards and found a two ford oem starters from 93-97 3.0 rangers with a manual transmission.
Fast forward to 2023, i needed a starter and went looking at oem new, rebuilt or used. Found nothing local, got on ebay and found a nos 3.0 starter rated for a 93-97 3.0 aerostar.. well all aerostar vans in the 90s were automatic. Internet research, talking with ford local and in Detroit. Ford in Detroit did say a starter from a 3.0 automatic will work on a 3.0 5spd. That was my question..I bought the starter to install it, and was still going good until my 94 was totaled. I have a 97 3.0 5spd ranger now, and I have spare starter from a 3.0 automatic I picked up last year from the junkyard.
Long explanation, what i did discover is a 4.0 automatic transmission starter will not work on a 4.0 5spd transmission. The same with a 2.3. The 3.0 starter is the only one that will work on both. My suggestion is instead of buying a new or rebuilt junk from the auto part store. Go where the real junk is and find a good used oem starter from a vehicle at the yard. Then have it tested at the store to make sure it's good.
For your needs, I say any ranger from 91-99 4.0 5spd will work, it all the ohv engine. Any 91-99 explorers 4.0 5spd will work..just make sure 95+ explorers has the ohv engine not the sohc engine. Most 4.0 5spds were in the explorer sports of those years. Get a starter from a 5spd trans only, not an automatic.
Hope this helps