The likely list of suspects:

Air bubble in your cooling system
Vacuum leak
Idle Air Control Valve
Fast Idle Thermo Valve


"ldan" <ldandridge@excite.com> wrote in message
news:1165331329.969397.237390@j72g2000cwa.googlegr oups.com...
> The engine on my 1990 is racing--reving up to 2000 rpms then dropping
> back to 1000 rpms--continuously while in drive and also while idling.
> Any ideas what could be causing this problem and how to fix it?
>