bucking/stalling under any kind of load?

[ncsdaonex]

Ok I have a 94 ford ranger 4.0l v6 5 speed ext cab 4x4 ranger. Heres how this project started, bought the truck totalled, put another frame in it, then removed front end from cab and drilled out spot welds, replacing front end soon, next thing i converted it from automatic to manual, okay so after i put most of it together heres list of problems that im unsure of, also the harness that went to the auto trans I removed and just left no harness connected to the back of the engine where the connector is, so problems are main one when u start it u can rev it if u lightly hit the pedal, but any more and itll buck and die out and try to shut off and back fires and carrys on, now if i disconnect the maf engine will rev fine but then I get a check engine light, now wether its connected of not when u try to drive the truck as soon as u let the clutch out lightly it will try to stall the engine no matter how easy or hard u try to pull out, even if u drift down a hill and put it in gear and give it any gas itll just shake the truck from bucking and motor dies out, also when it does this I notice battery gauge jumping all over the place, other problem is my oil light only comes on when i crank the engine over then goes away, the oil pressure gauge doesnt do anything either but ive had this engine running for 15 min already and reved it a bunch and runs smooth no tapping or smoke or anything so i know its gotta have oil pressure so must be wiring problem but not sure where the sending unit is on this motor. last problem is when i plugged in the clutch master cylinder wire into it the truck wouldnt crank so i spliced the wire off the ignition straight to the starter solinoid and it cranks fine just cranks wether the clutch is in or out but thats no big deal. So anyhow theres a big detailed description main thing is y is it bucking and not drivable but idles fine, im assuming maybe bad ground but u guys would know better, and wheres the oil pressure sending unit?