Acceleration Problem

My small block has been running great up until yesterday. I had not driven it for two weeks started it up and as I strarted down the road the car was bucking, back firing and breaking up badly. I came home and replaced the rotor, checked the fuel filter, pulled the plugs and found 7 out of the 8 were wet. When I am uup around 2500 RPM it seems to clear a little, but as the RPMs lower it get real bad. Before I had put it away two weeks ago I had added Lucas Fuel Treatment. Up until that time the car had run great. It feels as if I have water in the gas. Could this additive be the problem? I have an MSD systm on the car. I really dont know how to troubleshoot that. I am wondering if I remove the old gas if that will help. I have checked the wires and distributer cap. I am at a loss. Any help would be appreciated.
Thanks
Mike

Does it blow smoke? It could be a stuck float in the carb.

You're either dumping a ton of fuel into the engine or your ignition system is dying. As for troubleshooting the MSD, I would contact their tech line (www.msdignition.com or 915-857-5200) directly, I'm sure they would help you out. Its more likely though that it is a carburator problem, the stuck float sounds like a very real possibility. Be careful, stuck floats can lead to fires, especially if its a Holley.
Good Luck!