back firing problem

[gorilla]

I am posting this for some help. I have a 1989 335is turbo which right is runninig very poorly. I have rrfpr and a chip which does pretty good the only problem is it is backfiring and hesitating upon acceleration and I can't figure out why. This only what I thgink right now 1. really bad fuel 2. fuel pump not strong enough to support turbo system 3. exhaust leak which makes no sense ran it up on boost today ran perfect and only running 7lbs. Idle fuel pressure 20-25 psi. any help very much aprreciated

[Need4Speed]

Would need more info about your system and what is going on.