Stumble, high idle
I was driving my 87 -930 at a steady 50mph ( wife was with me and I had to behave ), when she started to run rough and stumble. I thought she was going to die everytime I had to slow, I kept the revs up around 3000 and made it home about 2 miles. For the last 3/4 of a mile she ran fine. When I stopped I notice the idle was steady at 2000rpms while stopped. I shut the car down and restrted..same thing 2000rpm idle. I started the car the next morning ans she wanted to die after idling at an unsteady 300-500rpms. I kept her running by keeping the idle up around 2500 for about 20 seconds. After that she ran smoothe but the idle was steady at 2300rpms.
I am not overly concerned, I know I didn't break anything major as she isn't blowing, smoke, knocking, missing, down on power, has boost, etc. My mechanic thinks vacuem leak, auxiliary air valve or maybe WUR. What say you??? Where would you start??