I had the same problem with my 1990 4.5. I used the A/C panel diagnostics and the service manual to get the ISC and TPS calibrated correctly. The problem was gone. Both ISC and TPS MUST be set up together.
Joe McKinney, TX
Dave,
>
> I did the fuel injector test as suggested by bbobynski in the caddy group. Sure
> enough, I had one locked open fuel injector.
>
> I will do the ISC switch test tomorrow. And also test the TPS.
>
> I haven't as yet used the diagnostic mode of the A/C panel yet, except for
> pulling codes. But I do have the documentation on how to use it (from > Mitchells)
>
> Bill
>
> On Thu, 18 Mar 2004 17:09:02 -0600 (CST), snipped-for-privacy@webtv.net wrote: >
> >>one error code: E30 - ISC out of range.
> >
> >Bill, do you know how to use your Diagnostic system? Reason for asking
> >is because the switch test needs to be done.
> >
> >The ECM must received accurate switch status info in order to control
> >idle. Many engine and emissions system faults may cause your problem. > >
> >The TPS may be out of parameter adjustment. Also an out of adjustment
> >air rate, ISC or TPS can cause the ISC not to control idle or code E30
> >to set falsely.
> >
> >E30 is designed to detect engine RPM out of limits high or low. > >
> >Dave S(Texas)