Yet another Idle question.

[Trigger Jack]

First, yes, I've searched.
Vehicle is a 1997 GST.
Anyway....Recently pinged the error code for the ISC, so I went ahead and replaced both that and the fiav. The car now holds a perfectly solid 1500rpm idle in park, and a 1000 rpm idle when in gear. When slowing down, as I approach about 10mph, the car shudders hard, once, but no loss in idle or anything else. No loss of power at speed, or any other time. Idle doesn't fluctuate, just sits perfectly at either 1500, or 1000, depending on park or in gear. Prior to all this, it sat at 750rpms, regardless of whether in gear or not. I reset the ecu, etc.....don't know what to test at this point. Help would be much appreciated. Thanks.

 

[JessesTalon]

Have you tried adjusting the BISS? It may be leaking.

What kind of shifts do you get normally, does it feel like its shifting hard, early, late?

 

[Trigger Jack]

Haven't adjusted the BISS yet. Just read up on how to do that, might try that next.

As far as shifts go, it's shifting the same way it was before I swapped out the ISC. I just drove it around some, and it's at exactly 18mph when decelerating, that I feel the shudder; not 10mph like I mentioned previously.
Only other thing I've noticed, is that while driving, the rpms slowly drop off, even if I keep the gas pedal at the same position, on a level road.

This is really frustrating, as I wasn't experiencing any problems before I tried to fix it....just had an error code. Almost seems like I should go back to the old ISC.