backfires

My 1995 230 OV 5.7 has a problem that has gradually worsened over two years. When I quickly throttle up the engine backfires, now to the point it will not get on plane. With a very s-l-o-w throttle application it will ultimately plane, but it takes a deft throttle hand. Maintenance items like...

ok i have been messing with this motor for a while now. It seems to no power when i give it full throttle. it will start backfiring when i use the trim controls or the tilt. its a 21' searay cuddy walkaround with a 305 gm motor. i just had the carburator rebuilt which cost alot. its a edelbrock...