1996 Jeep Laredo Engine wont start backfire through throttl

Hello I have a 1996 Jeep Grand Cherokee Laredo 4.0 inline 6. I drove to work just fine and noticed nothing with it then half a mile down the road it died out, the gas gauge was kind of low at the time by the only way it started back up is if I floored the gas pedal and I couldn't let go of the pedal or else the engine would die out, made it to the gas station put gas in and then made it back to my work by holding gas and breaking while drove. It finally started without pushing gas to floor drove around parking lot and died through a puddle. Left it there and next morning engine started find by itself then tried to drive and would only work if flooring gas pedal. Tried running it at home it took alot of times to crank but when engine ran it was rough and would die out if touched gas or put in gear or after 30 seconds. Then engine doesnt start at all and am getting a backfire through the throttle body when it does try to start but it never does. The smoke is white. There is also a coolant leak from the front away from the engine by the radiator, I dont know if that has anything to do with it or if its just coincidental. I changed the spark plugs but didn't help. Also there is no coolant in the oil and the oil level is full. When it backfire it also blew the oil dipstick out. I know there is many parts it could be but was just wondering what some of you guys think. Any suggestions would be appreciated thanks.