High rev for no reason

Several months ago I had a gentleman on this site reply to me regarding
high rev while highway driving. I don't recall what he said and
can't find it in my mail. The 94 SW2 with 80K on the motor & trans
would suddenly increase RPM's up to around 3K I would have to put it
in neutral and rev up a few times before it would drop down. Any ideas?
I restore Brit cars and bikes so I will understand the response.
Linda

 

My first instinct would be to clean out the throttle body. Next, I would
suspect problably the EGR valve and have it inspected.

marx404

 

I would say its the Engine Coolant Temperature sensor. Being a 94 its
the one going to the ECM, not the one going to the dash gage.

Also a check engine light means "get the code read". No reason to make
guesses. Some big parts chains do it for free.

 

What is the ECM is that the cap or something else?
Linda

 

Engine Control Module.

Hard for me to remember that... after 13 years working in a military R&D
facility, every time I read ECM, I think "electronic counter-measures". But
that's a different story.