A couple weeks ago, I tuned-up my '92 245 with 191,000 on the clock. New plugs (properly gapped!), new cap and rotor. Shortly thereafter, it started to idle rough. I checked all my vacuum lines but found nothing disconnected. I thought it may be a bad tankful of petrol since the problem started just after my last fill-up. I have since filled it with petrol from a different station, but no change. It runs fine at cruising speeds and my mpg has not suffered, but its embarrassing AND frustrating to be sitting at a red light in a brick that jiggles like a huge vibrator! Lately, it has been around 50 degrees in the morning. When I first start up, smooth idle! As is warms, it gets more choppy. Ideas, please!!

-Doug

 

Try cleaning the throttle body and idle motor.