Running rough after seafoam

I have a '93 Regal GS with the 3.8L and it ran fine but I noticed it didn't have the power that it used to have. I put some sea foam in the gas tank and noticed a little improvement. So I read on the bottle of sea foam and it said you could put it in the crank case and also run it through a vacuum hose in to the intake. So I disconnected the brake booster hose while it was running and poured some seafoam in a little at a time then I shut it off and let it sit for about 20 minutes. I also poured the reccomended amount in the crank case. Then I started it and took it for a test drive down the highway, it ran great. Then I took it home and didn't drive it till this morning. I started it up and it runs like crap it sounds like its missing. Itll still get on the highway fine and drive around fine but it sounds likes its going to die and when I rev it up in park it revs up then drops down to a little below idle and sounds like its going to die and then goes up to idle. Im clueless, I had a vacuum hose that was dry rotted I replaced it and changed the oil because I had the sea foam in it.

I would check to see if your spark plugs are fouled, I've heard of people fouling thier spark plugs after using seafoam. Depending on when the last time they were changed it prob wouldn't hurt changing them anyway