There was a recall out for leaking o-rings on the injectors for these engines. If your Dad has owned the car from new, he probably had them replaced at the time of the recall, but its worth checking out.
If you can't find a manual (I got mine from ebay) you might wan't to check out alldatadiy.com I got the picture from there. There is a bunch of useful information on there, and it is almost as good as having a manual. Sometimes better.