Misfire on Acceleration only ??

[fast cars]

My Little Merc C200 1999 auto will start up , idle and rev up fine whilst stationary , but on the go , will only accelerate smoothly if you go real gentle on the throttle ; anything quicker results in what sounds like backfire/popping in the inlet manifold ! can anybody give me some advice on what I should be looking at to cure this ?

Thanks

Danny