My 92 Taurus wagon does not idle correctly (engine diesals) in Park. If
you put it in gear it idles just fine. What's going on?

"engine diesals" (sic) is where the engine continues to run (badly) for
a little while after the engine is shut off. If your engine is surging
or hunting for a steady idle speed in Park, the most likely problem is a
dirty/worn idle control valve, a shiny metal cylinder bolted to the
throttle body. See: http://tinyurl.com/23cjdn

Do fuel injected engines diesel?

Just about all diesels ARE fuel injected, & have been for a long time...

Rob

ROB, get a brain.

He was asking if fuel injected gasoline engines diesel.

The answer to that is yes they do. Especially if they have leaking injectors
they can diesel.. It isnt common for "dieseling" to occur in a fuel injected
gasoline engine, but I have seen it happen, and it was usually due to
extreme leakage from atleast 2-3 injectors..

Ford Tech

I dont think what your car is doing would be accurately described as
dieseling.. Dieseling only happens when you turn the engine off, and it
continues to run.

I think what you are describing is called "Hunting, Surging, or Rolling
Idle". This is where the RPM's on your engine are NOT stable at idle, and go
up and down as if they were on the ocean. Hence the term "Rolling" like
waves...

I am with Sharon Cooke on the diagnosis here as well.. Check the IAC
valve.. Possibly just replace it..

Ford Tech

Thanks.