rough acceleration and idle

[4cyl..guy]

I bought my '98 4 cyl. 4runner with 100,000 miles on it.
It ran ran great until recently, 137,000 miles, it idles slightly rough, but upon acceleration from slow speeds or from a stop it is "sputtering" and hesitating slightly.
The plugs, wires, oil, fuel filter, pcv valve, air filter... are all fine.
...oh, and no "check engine" message.
Can anybody point me down the right road to diagnosing the problem?

 

[ToolmanJohn]

I bought my '98 4 cyl. 4runner with 100,000 miles on it.
It ran ran great until recently, 137,000 miles, it idles slightly rough, but upon acceleration from slow speeds or from a stop it is "sputtering" and hesitating slightly.
The plugs, wires, oil, fuel filter, pcv valve, air filter... are all fine.
...oh, and no "check engine" message.
Can anybody point me down the right road to diagnosing the problem?

Try a couple cans of Seafoam. Follow the directions. This stuff works on cars with carbon buildup on injectors and valves. Dump two cans in a mostly empty gas tank then fill it. It worked pretty good on my brothers 1995 Taurus. We were both suprised. Fixed his shoddy idle, and it responds to the gas pedal in much less time than before.:

 

[4cyl..guy]

Well, what I did was I removed the Mass Airflow Sensor and cleaned it. Then, upon closer re-inspection of the spark plugs, I noticed the number 1 and 2 plugs had some wear on the tips. I replaced all four.
I then added a bottle of chevron techron fuel system cleaner.
Whatever was causing the problem is now gone.
...now if I could just get it to do an 11 second quarter mile...

 

[ToolmanJohn]

That Techron stuff is supposed to be pretty good too. I did a lot or reading, and I couldn't find many complaints about Seafoam. Just a lot of praise.

 

[4cyl..guy]

Seafoam?
I've never heard of it. I'll have to check it out. I've never been big on additives, simply cause I think most of them are just alot of BS in a can, but I keep an open mind when someone tells me they found something that works.
Who makes it?

 

[ToolmanJohn]

Their website

http://www.seafoamsales.com/motorTuneUp.htm


Also check yotatech forum, there are a LOT of writeups on this stuff.