can anyone help me out and let me know how to fix these codes??
Im getting desperate, can't afford garage labor
Going off what is being said-091 code PRNDL- the computer is not seeing the correct gear selection coming out of the PRNDL switch. It could be out of adjustment, this isnt that bad. The 098- high rpm is the computer seeing a high rpm reading when you select a gear from park. This is usually caused by the ISC motor being bad. If you said you noticed it running at high rpms, this could very well be your problem. Get yourself a factory shop manual. Hynes/chiltons are no damn good. There are steps for replacing the ISC motor- more than just replacing it- You need to let the computer relearn the settings.
My 91 Deville had the same problem, turned out to be the idle speed control, the thing would get hung out, and keep the idle high? Maybe this will be some help, don't know if they are the same motor or not.