G20 Problems

[4cefed1]

I'm new to this forum and know NOTHING about these cars...I'm into Powerstroke diesels and active on forums geared towards them. Anyhow, my dad bought a 99 G20 with about 120k on it, problem is the car has a hard time starting when it is cold, it cranks and cranks backfires a little bit and then fires off, we have replaced, the crank sensor, e-vap or map sensor on top of the motor, and checked the fuel pressure to make sure it is holding, car has no lights on and im sick of throwing parts at it any information would be appreciated.!