EH? could be a number of things, I recomend getting a OBDI reader and checking the codes, could be 1 bad reading from one sensor causing that. You can try
Stealth 316 Home and reading about how to read the codes with a analog meter, but its not that easy. If you are planing on keeping the car I suggest you buy something like this.
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I have one and Im glad I do, I can check codes, and view each sensor to see how they are working.
Good luck.