99 interstate runs rich, idles fair , has KnN filter

[Eric58701]

ok I haven't spent a whole lot of time on this issues as my job in that past two years has been 70 80 hour weeks, this summer I told them that's not happening or I will go rip tickets at the movie theater.
 anyhow it worked, I am back to normal 50 60 hour weeks lol.
 My 1999 interstate I bought a couple years ago, smells really rich and runs a bit rough just off idle, and goes like a raped ape at top end. I looked into the Air filter the first summer and found it has a K and N filter, so I left that, I should have taken it out and put stock in and cleaned the KnN but I  didn't.
 So I was thinking I might try a new degree wheel to advance the timming,  and then maybe rich will be ok ???
 my mechanic said he wont adjust the carbs until I put stock air filter in or clean the KnN as he says it can or might be over oiled.
   what should I do ? you more experienced guys usually have great input

[Ricky-D]

Clean the K&N, no pre-filter and add some gasoline additive to the tank. You can install a degree wheel but, it won't have much affect on what you are concerned with. If you can run non-ethanol gasoline, I would strongly recommend to do that.  I suggest to do nothing else, the additive should clear up the stumble after a while.

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[Eric58701]

i have never cleaned a K & N filter, I do have the new OEM filter sitting on the shelf, I  filled up the tank this weekend I will get some fuel  additive to the tank and ride it till the tank is empty, so its not so dam heavy when I attempt the filter clean.

[John Schmidt]

To clean my K&N I just went to an auto parts store and picked up a cleaning kit. Has the cleaner and the oil in it, just don't get too heavy with the oil. And like Ricky said, leave out the foam prefilter if it has one installed.

[Eric58701]

it does have the pre filter, I remember  that, so why leave it out?

[John Schmidt]

it does have the pre filter, I remember  that, so why leave it out?

'Cuz it isn't needed in most applications, yours might be one of them. I've found the majority of K&N installations don't use that prefilter. Helps to make it run more lean if left out.

[Eric58701]

lean is what i need, its rich and stinky at low speeds and idles rough.

[Ricky-D]

Those are two individual complaints, and not necessarily related.

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[John Schmidt]

I'd try it without the foam filter for a couple hundred miles, maybe less, then check the plugs. If it still feels and smells rich but not as bad, you might need to set your pilot jets in a tad more, then get your carbs sync'd. Just do one thing at a time but I think you know that.  

[pancho]

Sounds like someone may have opened the pilot screws trying to compensate for clogging jets,,,  like RIcky-D said, first thing is to run some carb cleaner through it,, Chemtools B12 works for me,, about $3 at WalMart.  I'd put the stock filter in, yours MAYBE causing the problem.