Just recently bought a 1994 Chevy G20 Van. 3spd. Auto w/OD, A/C, ABS, Drivers Airbag, 2/3 side door. No owners manual. Second engine. Original is 4.3 liter V6. How can I find out what size and/or year

Just recently bought a 1994 Chevy G20 Van. 3spd. Auto w/OD, A/C, ABS, Drivers Airbag, 2/3 side door. No owners manual. Second engine. Original is 4.3 liter V6. How can I find out what size and/or year the current v6 is that is in it now?also;;... 1) Idols fast like the choke is stuck on, but increases in rpm, only to a certain point. Maintain's fast idle the whole time it's running, except when in gear. 2) Bangs into gear when coming from park or neutral going into drive. 3) Blows cold air through all functions the heater control panel. Temperature gauge appears not to go above 100 degrees. Had leak down side of radiator. Put in some bars leak heavy duty stop leak as first attempt before having the cost of a new radiator. The leak has stopped. I put a new radiator cap on as OE cap was in rough shape. Seems as if the AC unit pump is continuously going on and off. 4) Would like to have wiring diagram for whole vehicle, if possible. 5) Door hinge pins for drivers door. 6) How do i eliminate the condensation from the inside of VAN before I install interior? To insure that it doesn't rot out. 7) What type of rear end comes stock? I apologize for the gamut of questions. I'm hoping I can get some quick answers to all these. So I can get through these minor problems as quick as possible. Picked it up for only 800 bucks. Not too bad of a deal, I think, considering what else was out there for under $1000. Thanks for any help I can get on these issues. [email protected] Britt