Thought I'd share my experience with Seafoam. This first paragraph describes everything a friend and I did and if you don't want to read it all, just know it helped but the car would still would chug at lower RPMS. The second paragraph is about the Seafoam.
I bought a turbo charged Fiero with a 2.8 that did not run well, it ran really rough at lower RPMS and at times it would bog almost completely and have almost no power. I did a bunch of stuff and did a quick test drive after each one to see how if effected performance. Fixes include cleaning contacts at PCM, helped - cleaning all the plugs I could find on the engine, added ground strap block to battery ground, helped a bit - new TPS sensor, helped - new oxygen sensor, helped - checked if timing belt had play, it's fine - new ignition control module (in bottom of distributor), helped - new cap and rotor, helped a little - new wire from distributor to coil, checked for spark leak on plug wires, none - oh yea, first I pulled gas tank and it is clean as new, added new fuel pump, sock and fuel filter, we tested fuel pressure while driving and it is fine - reset timing - checked for vacuum leaks - unplugged tach filter, no difference. It has no EGR or charcoal canister. Pulled a spark plug and it looked fine. Everything added up and it no longer bogs down, but it would still chug at lower RPMs, up to about 2500.
SO, finally decided to try the Seafoam I had bought. My buddy was skeptical, he is a pilot by trade and owns 4 Fieros that he keeps in top running condition, including a 3.4 he did. I was skeptical too after watching a Youtube video where a guy demonstrates that Seafoam creates smoke even on a brand new engine (most people claim it is the result of carbon burning off). I DID also pour a LITTLE bit of water in before and after the Seafoam, but it was ONLY 2 oz. of water, literally, I measured it. Okay, so I got it up to running temp and started adding the Seafoam in through the throttle body and brake vacuum line at the manifold. The weird thing is I did not get ANY smoke, at least not from my view at the engine, couldn't see the pipes directly but there were NO plumes. I used 1/3 of the bottle. Started her back up, wouldn't start. Tried again, started second try and instantly it went into idle at about 800 rpm, something it had never done before. Revved it a bit, not much stumble. Got in to drive, stumble was reduced the most it had been to date. Got pretty excited and we decided to add it to the gas as well. Added 1 oz. per gallon, so now I had about 3 gallons of gas in her and took it out for some spirited driving. It gets up and moves! The stumble is still there, but it is greatly reduced, now capable of being a daily driver. This stuff works, there is no doubt about it!!
Still to do: pulled off upper intake and am going to clean it up, we wanted to check vacuum lines. Cleaning throttle body too, it is still pretty dirty which is admittedly odd because I did add about half the S.F. there, but the butterfly valve was nearly completely closed when I did so it didn't have much chance to do much there. Also ordered an Accel coil #140008 which my friend recommended and am shopping an MSD 6a ignition module. He says they make a world of difference, boosted his gas mileage to 32-35 on the highway.
In a related note, check out this video on Bestline oil additive, I'm planning to try it, it looks pretty incredible.
https://www.youtube.com/watch?v=A-bU6SByP0Y Also, I was thinking about the economics of gas additives, the same concept applies to oil additives. Say there is a gas additive that costs $12, and you put $3 worth in your tank at every fill up. That is a bit less cost than one gallon of gas. If it helps you get 3 mpg better mileage, with a 10 gallon tank, say you got 20 mpg before, 23 after. You go 30 miles more on one tank of gas, or the equivalent of 1-1/2 gallons of gas for the price of less than one. It basically does better than pay for itself, although at these numbers not by much. You would however have better performance, cleaner engine, etc. Again, same concept applies to quality oil additives, they now seem worth it to me.
