IDLE PROBLEM??????

[Pat and Dallas Larson]

Hi Gang, My Ercoupe (N93555 pictured in [EMAIL PROTECTED])  just developed a rough-running problem at engine rpm 1000 and below.  I had no problems during my three-hour flight back from Oshkosh last Monday.  Didn't fly it until Friday as I wanted to warm it up before doing my 25-hour oil change.  After I started it up and taxied to the fuel pumps, I noticed it was running rough at lower rpms.  After the fill, I started it up and proceeded to taxis to the  runway for take-off.  After taxing about twenty feet, it quit.  I primed it twice and started it up again.  I proceeded to taxis  at 1200 rpms to the end of the runway and did my run-up.  I flew it for nearly a half-hour and then landed. No problems in the air!  When I pulled off the runway to taxis the engine stopped due to low rpms.  However, it started up immediately. I believed I primed it once.   Then I believe I taxied with the carb heat on which seemed to be a marked improvement.  I returned to my hanger and proceeded to change the oil and also cleaned the air filter, which was quite dirty.  I thought it might not be letting in enough air at low rpms.  At higher rpms the prop would be forcing a higher volume of air to the carb.  As it was parked, I ran it without the air filter in, thinking that there would be no restriction to the air flow.  Still ran rough and killed several times.    Saturday, I asked a couple A&P mechanics their opinions.  Didn't get much help as they weren't too adept working with carbs.  I proceeded to experiment on my own.  When it would just about die, I would pull the primer and it would respond dramatically, then shortly start running rough again.  Or, after the engine was warmer, I would pull the carb heat when running at rpms 1000 and below. Ran pretty good then. I also turned the adjustment screw both directions(without the carb heat) one-half turn at a time up to a full turn with no appreciable results.  One A&P said that I was too fussy and that these older antiques just run this way.  Well, it had been running great up till now and I don't buy that  idea anyway.    Today, I flew it two hours. No problems in the air.  After my first landing, the engine stopped as the rpms were around 700 as I was turning off the runway. I didn't have the carb heat on that time.  From that point on I left my carb heat on for rpms 1000 and below.  No problems. I'm not comfortable having the engine perform this way.  HAVE ANY OF YOU HAD A SIMILAR SCENARIO AND COULD  RECOMMEND A SOLUTION TO MY PROBLEM? I will have a qualified mechanic perform any corrective procedures that will be necessary.  Is there an idler jet that needs to be replaced?  Do carb floats get out of position and stick?  Is the engine not getting enough fuel or air or both?   If any of you can shed some light on this subject, I would be most appreciative.  Thank you in advance for any information regarding my dilemma.   Dallas  Dallas & Pat Larson Lakeville, MN 55044 [EMAIL PROTECTED]