So - after a new crank sensor, thorough cleaning of throttle body/IACV/MAF/hoses and Seafoam - she's been running smooth for about a month now.. Idle steady at +-700rpm.
This morning, she zoomed to 2100rpm and stayed there. Shift to Drive, and like a horse straining at the leash, she sped up. Had to slam the brakes. Driving to the auto shop and riding my brakes, she'd stay at high idle and went down to 1300rpm only if I shift to neutral. Would also lurch lightly right before every full stop. Parked to talk to the mechanic.
Came back after two minutes to drive her in - and it was back to normal 700rpm like nothing happened. No codes, and had a nice two hour drive at 65-70mph.
Is she just schizoid, or is this symptomatic of something more?

 

Mine did that few times before the IACV crapped out.

 

at least buy the autozone spare chevy 1989 astro IACV, put that one in and report back.

Solved the majority of idle issues I had at the time. Not as good as genuine but good enough.

 

Just a headsup, the IACV from a '89 chevy (eg: SMP: AC1) will not work on a 1996 DI with a 4.0 (OE #: ERR4352 or SMP: AC592).
It's OK for a DI 94-95 with a 3.9

If your IACV Connector is F'd up Standard Motor Products (SMP) also makes a replacement S-551.

 

Thank you gentlemen. The freakout hasn't returned - but will keep a spare handy until the next occurence. Just curious.
The part's cheap enough and easy enough. Happy Holidays.

 

Probably a $15 part

I had that happen once and it freaked the h.e.double-toothpicks out of me. Never happened again and that was at least 2 years ago. Rovers are weird. Lovable but weird.

Happy Holidays!

 

I just had a similar symptom. It was the result of a low battery. I let it run 30 mins just to charge it up. The next time I turned it on, back to normal.

 

weird - and wonderful. I'd been driving all day before it happened, so it wasn't my battery.
a few days now, and the symptom has not returned.
.