Stumbles/misfires/ sputters

[cole]

Hello. I cannot for the life of me figure out what is wrong with my bike and I'm losing my mind!

2005 GS500
38K

It seems to run fine around the city, no issues, like a dream. Now, when I get on the highway and want to accelerate it sputters. It seems to run fine at a constant speed, except when acceleration takes place. Now, I have no issues at city speeds ~50 MPH. After the bike is extremely hot, the idle drops extremely low and sometimes cuts out. I have adjusted idle to about ~1400, it appeared to be set closer to 1000.

I just checked the battery where I got it - checks good. I just had the carbs cleaned and it runs better than before - no longer an issue around the city though may be due to replace of coils. I just replaced the coils . I replaced the spark plugs. I have seafoam in the tank because it was sitting due to frustrations though my bike has never exhibited the symptoms with seafoam in the tank. I did ride with bike at highway speeds with the gas cap open though they made no difference - so my vents aren't clogged. I did have a recent major service (before my problems) though ever since then, I've had issues with the bike; they adjusted valves, adjusted cam-chain, synched carbs and they had issues with my floats, I took it back repeatedly and the bike ran okay afterwards. I've never taken my bike back to them.

Now, on a hunch I did check the air filter - which I replaced at most recent major service - and it's light brown. Would a clogged air filter exhibit these symptoms at speed or is it something more dire. I'm tired of throwing $ at the bike with no solution.


I'm truly at a loss. Please help and sorry for the LONG post.