Rich/lean problem and backfire
 

Iam having a problem with my fc. When i turn on my car, iam fine i can red line it no problem but the moment that i am driving it for a while then i turn off and turn car back on like 5 min later and i try to take it to 4 rpm my car go from rich to lean and then it shows nothing but one lil line in the lean and then it starts making a noise like if it is backfiring and the car doesn't wanna keep on going up on the rpms so i have let go of the accelerator and then press it nice and slow. Can someone help me plz?