Car seems to idle okay when it's cold, but once it heats up, it idles speratically. Local mechanic (and friend) says to replace the fuel filter first to ensure that the engine is getting proper pressure to spray fuel correctly. It's cheap and I think I'll start there. Any insight would help though! 89 Honda Civic 1.5

This problem doesnt seem to affect the performance much, it runs like a bat out of hell, but I know its not right and I want to fix it.[:-]

 

replace the vacuum hoses - cheaper;
if not already done so.
cannot tell bad hoses by looking.
that big one off of brake booster may be checkable (and probably ok)
cost is about 3 bucks

 

That was my next idea, I already bought some plugs for it and Im going to go ahead and do that and maybe play with the timing at the distributor first. Next will be checking vaccum hoses and finally the fuel filter, if this doesnt work, I'll need some more insight! >:O

By the way, when I had the head off, #2 and #3 cylinders (the middle two) had nasty white looking carbon build up on the valves. The other two had normal black carbon build up. I just hit it with some carb cleaner and chipped off what I could and made the valves as flat as possible without scoring them. Anyone know what that white crap was all about?