Mercedes 190e 2.6 auto,starts fine when cold but idles rough and hesitates for ten minutes untill warm then fine, starts fine when warm but idles rough and hesitates for 1 minute

Most likely throttle positioning sencer

Classic example of a clogged catalytic converter! I bet it will restart after two hours as well.

Here are the most common causes of idle surge, rough idle esp when cold and stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

go have the vehicle scanned for trouble code usually flashing is a misfire but have scanned so your not guessing as to what the problem could be most auto stores offer service for free

Could be the fast idle sensor check to see that the vacume line is hooked up properly.

1988 ranger 2.9 runs great cold then after a few minutes when warmed up hesitates with intermittent black smoke from the tail pipe until i hit the the throttle then clears and will repeat this behavior...

that means could be vacuum leak

sounds like your choke is stuck

cold start relay either the fuse in the relay, or the relay itself.

Mine did the same thing at 16K miles, I cleaned the throttle body and the ploblem went away. Took me about 30 minutes.