98 malibu difficult to start

Hi i have a 98 malibu. i just had a refrubished motor installed on the car and when i left the shop it started fine. when i started it later the night it took three tries to start up. and now it takes almost 5 minutes to get it to start. i went to advanced auto parts to see if they could hook it up to thier computers to tell me what was wrong but they couldnt find the plug to hook up the computer. does any one know where this plug it? they looked under the hood and under the dash drivers side. has any one resolved thier problem with it not wanting to start?also the gas gage goes up and down while driving. it drops down to E and the light comes on and then it goes back up and the light goes off. any one hod that happen.

I would take it back to the shop the work was done at, especially if they sold you the motor as well.