Did a seafoam treatment on my 88 4.0 xj last weekend by running almost 1/2 the bottle through the brake booster vacuum hose. Ever since its been running like crap, so I went ahead and did new plugs, wires, cap and rotor, checked all vacuum lines, replaced egr valve, but didnt change anything. Right now it's idling high (usually @ 1500) and when revving, seems like slow response and will sometimes backfire through intake.
Any thoughts on usual suspects that might cause this? Maybe the seafoam caused O2 sensor to go bad?
Any help would be great, thanks.

 

I've done seafoam on other vehicles and it will throw an o2 sensor code. I've always just taken vehicle on highway n opened her up. Could be a piece of carbon stuck somewhere. Sice you've replaced plugs not sure. Been told by a mechanic ," it's likely a carbon particle on a plug ( spark). Try running on highway for a distance. Aways good way to clear fuel n exhaust system of build up

 

Might have cleaned out some gunk that was plugging a vacuum leak.

 

You really gotta probably take her for a hard drive at high RPMs on a highway or somewhere safe. ITALIAN TUNEUP

 

Have you ever visited my website? I would do Tips 1 through 5 first.

I'm not a seafoam fan.

 

I think seafoam is in bed with the dudes the make cataclysmic converters.
"The smoke show that killed the cat".

 

I agree. I've only ever run seafoam on old motorcycles that don't have cats, or mufflers for that matter lol. Ran it through some small lawn mower engines too but definitely not in my cars. Turbo is right about it eating "cataclysmic" converters lol. It's destroys the precious metals inside.

 

Alright, a little update... I was messing with the egr solenoid today, what I noticed is that when I unplugged the power to the solenoid, it started pulling vacuum to the egr valve and the idle dropped to around 700, although a little rough. When I plugged it back it, idle shot back up between 12-1500 and the egr valve side of the solenoid was no longer pulling vacuum. I was able to see the plunger on the egr valve move in and out as I was doing this.
Is this normal? Or does this mean the solenoid might be bad? Tired of throwing money at this Damn thing! haha

 

Do the Tips suggested. They're free.