I had similar bucking problems on a previous car. Any time I lighltly tipped into the throttle with a gear engaged, the car would buck and lurch forward. Not nice unless you want coffee stains on your shirt.
The problem was a crack in an intake hose between the MAF and the throttle body. This crack let in enough unmetered air to throw off the fuel:air mixture significantly at part throttle. WOT was never a problem because the amount of unmetered air relative to metered air was very small.
Anyway, a little duct tape on the intake pipe eliminated the bucking, and verified that that was the problem.
So, for all you with bucking problems, I would look for a source of unmetered air.
