I HAVE A 300SEL 89 AND HAVE A ROUGH IDLE FOR A LONG TIME. THE TECH TOLD ME IT COULD BE THE MIXTURE CONTROL UNIT BUT DUE TO THE COST I DID NOT FIX IT. I DID HAVE MY INJECTORS CHANGED A FEW YEARS BACK. WHAT EXACTLY DID YOU CHANGE THAT CURED THE PROBLEM. APPRECIATE A RESPONSE FROM YOU.