Black smoke, high idle? what signals fuel rate change, idle control motor operation and changes/locks timing in the ECM which can promote clatter in a over fuel condition? Does the clatter get worse with engine heat since less fuel is needed?

How does a loose throttle cable promote black smoke? Fluctuation at idle?

M&M isn't smart enough to always code a ETS sensor or other failures and is a simple creature.

A worn lifter or cam lobe on the exhaust side can do black smoke and clatter but a high idle condition happening at the same time is highly unlikely of a mechanical failure.

 

Not black smoke, white smoke that smells like a rich mixture. It.only "clatters" and goes into the 500 rpm fluctuation after it is completely warmed up, only did one run after reset and problem showed up then. May just replace ICS a little down the line, just because it's original, and things do wear out ( like me). Ken

 

I received my 98 flhtcui.abcdghklxyz ultra classic with 95 tle ultra sidehack. I've been down thru most of the exact ssme problems as you. Took 3 years to fix.
First, I had whitish thin smoke in exhaust and smelled oily.
Pulled cover for cam chest. Plastic breather gear was worn and breather stuck closed.
Replaced...oil smell drastically reduced. Blowby almost stopped.
Still get stutters and stalls when hot with difficult restarts unless coolled for few minutes.
Cps was starting to spew goo, replaced.
Didn't fix problems tho did run a wee bit better.
Exhaust was stinky rich, would get me high when slowing down and shoot light fluffy black flakes in exhaust.
Ordered new temp sensor, tested both with resistance tester, along with air temp sensor. Boiling water, ice water and room temp readings were all well within tolerance and all 3 temp sensors read within 3 degrees of each other from lowest reading to highest. Was not engine temp sensor.
Tested cks per the book, was not crank sensor.
Still running like poo, I made my own breakout box, actually, I made 2. Cost me about 100$$ each.
Tested just about everything I cou,d according to the book.
Was at a loss.
Pulled off the intake assy, chemically cleaned, had oil dripping and other sensors dirty.
Reset everything in intake. Set breather to vent to atmosphere with catch can.
Still run like poo, ran ,like a dog, would be great could, crap hot. But slow down and then it had power again, left turn, crap. No power in 5th gear, had to drop to 4 in order to run on interstate or 55mph up gentle hill or against wind. But had random periods of time it would run great.
I knew it was electrical. Figured a short somewhere, even procured new main engine wire harness, thank my, didn't have to change.
Turned out, my spark coil, (c.r.s., don't remember actual word) but front coil was bad. Didn't pass resistance test. Didn't throw bad coil code either.. EVERYONE......ALL OF EM...said can't be coil. The transformer is sealed in epoxy, never go bad..... well, front coil was not putting out 14,000 million billion volts.. Was more of a 2,000 volt spark that was just enough for a spark when looking at spark tester, but poopy spark so front jug would fire but way poorly.
Since front end of transformer (coil) was bad, rear spark voltage was jumping a little on front end of transformer so rear jug also had a weak spark, tho not as bad as front.
Replaced coil with simple oem equivalent for about $80 with shipping and after replacing it along with new spark plugs and cables and now I have a brand new bike that runs totally different than the dog I had.
Went from 18-21mpg and no power to 40mpg WITH the sidecar. And enough power to keep 70mpg on interstate and yet accelerate while in 5th gear.
Moral to my abbreviated 3 year adventure, pull the plug cables and air brain cable from your coil and test the resistance. I'd bet, you might have a fsi.ing coil that hasn't completely died yet. ALL based on what I am reading with your problems.

 

Thanks, NCO. I tightened the throttle/idle cables(new) so there was 0 slack at the linkage. That was it. Been running great since then, with the exception of no cold idle(rpm 5-600) but is fine as 40w is thick at startup with 30-35 oil pressure.
. Only thing is still 33mpg,30 double. Not much to do about that. Does seem to run a bit rich, but not over-rich.
. Seems we all have our M&M tales. Ken

 

And no problem running it up to 100+ on the hiway.
Rarely go over 65 though. Factory cam to my knowledge.. Ken