My truck had a pretty noticeable stumble at startup. Just did this and a new fuel filter at 151k. No O2 sensor check engine light so far but I noticed an immediate difference in startup smoothness. Not perfect but alot better. Going to clean the Mass airflow sensor, throttle body, and IAC valve next. Just got the truck and I'm trying to baseline it before doing anything fun.

Ive read this is great for running in the gas, but when applied to the intake I've heard it cooks the Cats causing failure has anyone had this happen.

I've done it multiple times on 4 different cars and have not had any negative experiences.

Best positive result was that my old 4x4 corolla which needed premium gas due to pinging under load was eventually able to run regular gas after several applications.

Gonna try this out soon. Just bought the seafoam today and did the spark plugs. Guess i should order an O2 sensor now anyways?

Stoked anyway. Trying to get some more MPG for a big roadie.

Just did this myself. Bought the 2 pack that had one of the aerosol cans with the little red straw and a regular can of seafoam. Did the straw first exactly as Tim did in his video; measured the distance from the plates and all. Took about 5 minutes to do with the better half holding rpms at 1500ish. Let it sit, went to start it, and there was no smoke or anything. Idle hadn't changed, engine vibrations felt the same, etc. I was elated first, meant it was clean and the PO took better care of it than most. Then I got to googling... A lot of people had this issue.

Fast forward a few hours and I decided to do it through the PCV hose using 1/3rd of the regular Seafoam. Ill admit that I was very timid after reading about hydro-lock, but I sucked it up and just went for it.

Using a 2/3rds measuring cup (close enough to 1/3rd of the can) I poured the Seafoam into a small Mason jar. I started the engine and pulled the hose, placing it with one hand at the lip of the jar. The other hand tilted the jar just enough to make Seafoam flow towards the suction. After about a minute I was done and left it alone for about 30 minutes. Started her up and poof, white smoke everywhere!

I'm not sure the spray DIDN'T work, but I know the liquid worked far better.

I stopped using Seafoam and went to Berryman B12. Lots cheaper too. I have had good success with Cataclean from Autozone to clean O2 sensors. O2 sensors can throw a code if they are slightly out of spec (getting old and or dirty) Cataclean is about $24 bucks but better than replacing an O2 sensor. I also check my oil level when it's getting close for a change and top off with Rislone or Marvel Mystery oil for a few hundred miles. Just my opinions.

I just changed the plugs and they were pretty sooty. Nice and black. If I do the intake I'd have to change the plugs again? Really don't want to.

No, you don't. Pull a few and check them. They are easy to clean.

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I recently picked up a couple bottles of the "High Mileage" Seafoam and used one for the gas tank and about half a can on a fresh oil change as per the instructions on the can. Ive been driving it for a week now and my performance has gotten much better with less lag when putting the pedal down. Ill most likely run another can in the tank on my next fill up before changing out the fuel filter.

What direction did everyone go with when changing out spark plugs after cleaning out the intake?