I have 2001 QC 4.7 and every time I stop at a light or idle the revs go up to 2500 rpm Intermittently and then back down to normal then right back up again.
How do I find the source of the problem? Is this a vacuum line issue, map sensor?

 

I had same problem,changed my tps,15 minute job, 33 dollars at Auto Zone. Idles about
700 rpm . Disconnect pos battery , turn key for 30 seconds, and all perrameters will be
set , and mine runs great.

 

If you haven't cleaned the throttle body recently, and the IAC valve do that too. The IAC passages can get pretty gummed up.