The OVP is usually bad, it is the red-top relay behind the battery with the fuse on top, check the fuse first.

Sounds like your cruise-control stalk/switch is bad, I've had one of those limp ones and replaced it, pretty simple about two hours to R&R the steering wheel and lower dash for access.

I have spares of both here in Holland, MI, if you're ever up this way we can swap parts in to troubleshoot the problems.

To get over 30mpg in an '87 you need to have a lot of things right. Bad alignment, dragging brake, delivery-valve leak, ... things will quickly conspire against you to keep you in the upper 20s if it isn't in good repair. Besides that, they only get around 32-34 when driven gently on summer fuel.

I HIGHLY recommend running RedLine Diesel Fuel Catalyst in the fuel to keep the injection system happy, all of my diesels seem to run quieter and with less smoke after a steady diet of the stuff. I know many will cry "snake oil", but it's a detergent base not a solvent base, so there's no harm in long-term use and a $7 bottle treats 150gallons, ... don't knock it if you don't try it I say (Autozone carries it). Many here like running Diesel Purge directly in the fuel pump, a lot of extra work IMO and solvent-based cleaners like DP can be detrimental to the engine over time and most of them are recommended to be done before an oil change to remove the corrosive components from your crankcase before bearing damage.

Anyway, let me know if you're on the good side of Lake Michigan.

__________________

Gone to the dark side

- Jeff