Iv an 89 535i and it has been liyin up for the past 8-10 months, started ok with jump leads but when i went to give a little throttle it started struggling then pop/bang blew the back box to pieces. Started it again and left it idleing witch is fine thinkin that the problem might be the plugs so at half heat (the plugs been hot) i tryed again only for the same problem with popping.

But when i give excelorator slowly it reves fine its only when sudden exceleration that it hesatates and bangs.

Any ideas???
A good can of carb cleaner might do the job but where?