Seafoam full can in the tank, now runs bad. Can this be fixed. how?

Seafoam's webpage says you can use up to 50/50 seafoam/gas and not cause a problem.

Seafoam is not going to knock carbon off the combustion chamber and clog the cat. Oil burning over a period of time can cause cat issues.

I had a guy put in diesel in his reg gas car. That was a problem!

 

The only thing I would worry about with too much seafoam in the gas on a Gen2 prius is that it might damage the rubber bladder. Would seafoam be worse than straight gasoline, I have no idea. Actually it is kind of amazing that Toyota is able to use rubber this way at all.
"gas" is gasoline plus ethanol
Seafoam's msds shows >=75% "hydrocarbon blend" and <=25% isopropanol

Looking at a chemical resistance table for rubbers:

Rubber Chemical Resistance, Rubber Chemical Compatibility, Page 3 - Mykin Inc


LEGEND: 1 = Satisfactory, 2 = Fair, 3 = Doubtful, 4 = Unsatisfactory, X = Insufficient Data

solvent Nitrile EPDM Neoprene SBR Silicone Butyl Polyacrylate Hypalon Viton Polyurethane Fluorosilicone Aflas Kalrez
Ethanol____3 1 1 1 2 1 4 1 3 4 1 X 1 (in gas)
Gasoline___1 4 4 4 4 4 4 4 1 2 1 X 1 (in gas)
Isopropanol _2 1 2 2 1 1 4 1 1 4 2 X 1 (in seafoam)
other______ 1 4 2 4 4 4 1 3 1 2 1 X 1 (saturated hydrocarbons, probably in seafoam)

one observes that most rubbers are unhappy in gasoline, and of the few that are OK with it, roughly half of those don't like ethanol. Since "gas" contains both of those, that suggests the bladder is made of either fluorosilicone or kalrez. That would be a slight problem if the bladder is fluorosilicone because of the isopropanol in seafoam, but OK if the bladder is Kalrez. The "hydrocarbon blend" is most likely chemically similar to gasoline. I could not find a link to anything definitively stating which material Toyota used in the bladder, just lots like this one making guesses. The AI's are all pushing nitrile, as if ethanol wouldn't be an issue. Since Toyota seems not to have ever revealed which rubber they used, the AI's can only just guess.

 

Thanks for these details... I'm now even more convinced that OP bought bad gas and the Sea Foam part was not the cause of problem, just a coincidence.