Engine Hesitating when engine is cold

[Jungleman]

I have this problem of my engine hesitating in the morning when you hit the gas pedal, a pop sound come off the intake line to the air filter, (kind of backfires).
To make things worse, while doing a long distance journey after 3 hrs of driving the engine starts to jerk and loose power. Does anyone have ideas about what i should do? 94 isuzu trooper