what is this for?

Honestly, no idea why this came to mind, but it did. I had the silly idea to yank the 2.3 out of my Ranger and putting in an older engine, maybe a 2.9L into it. In my tiny mind my truck is a 1993, Last ones with the 2.9 were built in 1992, surely it'd be possible.... Right? I highly highly doubt...

Hello, My name is Leroy and I 'am the proud owner of a 94 Ford Ranger. It's a 1994 standard cab with a 4.0l and 5-speed transmission, it has 193k miles. I bought it with these Items replaced. Idle air control valve, Mass air flow sensor, Temperature sensor, throttle position sensor, new fuel...