1992 240 idle problem

My 1992 240 has developed a rhyming idle (speeds up and slows down in
a rhyming manner). This has been going on for a couple of weeks and
is almost to the point where the engine will no longer run.

Any and all thoughts and advice will be appreciated.

Thanks!

-- Frank

 

Check to see if any vacuum hoses have fallen off or cracked, this is the
most common cause of that problem.

 

If the car has a mass air flow sensor(located on the intake tube) try
tapping on it with the handle of a screww driver. If the idle levels the
sensor is bad. Or you could be looking at a bad Idle air valve. Agian try
tapping on the valve and see what happens. It probalby wouldn't hurt to
clean the throttle body too.

 

Our new addition to the family did the same so I pulled the mixture control
out washed it in fuel got all the crude out now its fine .Its under the
intake manifold has two pipes running from it with one electric connection
..Idles just fine now .My sons doing his learning on the 240 as had the
previous owners sons .