fan turns on when car is started and will not shut off until car is shut off. any
thoughts?  

The most common result of this condition I've found, is that somone has re-wired the fan relay/s for constant power instead of working from the temperature sensors on the engine.  To check this look at the wires from the fan relay/s and see if one of them goes to ground (frame/metal) close by. If so the temp sensor wire has been replaced with a constant ground activating the relay.
My fiance's 87 I have wired that way because we used to live in Biloxi, MS and she over heated it. My 91 was wired constant, but I re-wired it to factory.  I have tried to convince her to go back to the temp sensors but she won't here of it.
The fans are not constant duty electrical motors and this setup will shorten their lifespans. Exactly how much I have no idea, but I don't think its really that bad.
It also keeps the battery less than topped off because of the electrical load it puts on the battery when the engine is at idle and the alternator can't put out enough with the fans on all of the time. It's really up to you as far as what you want them to do, on all the time or only when the ECM senses that you really need them.