Originally posted by Rogerm60:
Welcome to CEG!
Misfiring is usually the plugs and wires (P0300-P0306).





The P300 - P0306 is often a lean misfire, caused by...vacuum leaks.

I personally do not believe that the problem, as posed, is your O2 sensors.

You have all the symptoms of a vacuum leak as described by other posters.

The hunting idle can be due to a vac leak or it may be due to a sluggish IAC (which, ironically, is a controlled vacuum leak).

My To Do list would be to service the upper and lower intakes paying special attention to all the vacuum hoses and the PCV valve, clean (replace if necessary) the IAC, and be on the watch for precat failure.

Steve

98 Contour SE Sport 2.5 Duratec ATX The wifey's car 89 Taurus SHO - 246K miles 94 SHO ATX - 190K 1997 F-150 5.4L ATX - The Workhorse 150K. ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!