Problem

A back-fire is an indication of timing being off, wrong fuel air mixture, or fuel pressure, a bad lifter or rocker arm,

What is the solution?

You wouldn't know the solution until some diagnosis is done. Start by having the trouble codes scanned. Write them down. Your definitely will have a miss-fire code. Fuel pressure should be checked along with a fuel pressure bleed down test. The trouble codes may indicate whats going on with the timing, like a camshaft sensor or something. The valve cover would have to come off to check the rocker arms, may even have a worn camshaft. Do you hear any excessive ticking from on top the engine? You just have to start looking at it.

Having the vehicle scanned for trouble codes are a big help. You want to start with the easy checks first.