Alright so I bought an 88 5.0 5spd a couple weeks ago with a salvage title due to the odometer being tampered with and a minor accident. The previous owners didn't take care of it cuz the coolant was clay brown and the oil was pure black. I changed the oil with Mobile One, replaced the filter, fuel filter, plugs, wires, cap & rotor, and coolant temp sensor. I also put air filters in it cuz the previous owner took them out. Ever since I've had the car, whenever I start it I have to give it gas for a good couple of seconds before it stays running or else it'll die. What do you think is causing that?

My second problem is that it idle between 1500-2000 occasionally and other times it'll drop to 800 and stay there. I'm thinking that is a vacuum line though, unless I'm wrong.

My third problem was that I gunned it down the street in 1st gear and once I let off the gas it died. Any help would greatly be appreciated.