Do intake leaks usually manfiest themselves as a rough, erratic idle, or is it possible/typical to get a smooth but jumping idle from a vacuum leak?

 

Most of the time, a vacuum leak would result in a rough erratic idle. If you have a smooth idle that pulses up and down, look at the TPS.

 

one easy way that i have been told to find leaks, is to have a buddy in the car, while your in front watching the engine. Have the buddy turn the car off, and listen for psss sounds. And vacuum leaks for me have messed up my idle.

 

TPS measures OK at the check connector and at its own connector (only did resistance there, not the JohnR voltmeter method.)

I do know that my crank angle sensor was needlessly replaced recently. (They thought it was bad because the car wouldn't start - turned out to be a "loose pin at the ECU.") Maybe that could be it... ugh.. can't even do timing until I get it to idle...