Cadillac Repair: engine cuts at idle sometimes smooths out, spark plug wires, climate control

Question
Iwould like to know how to check on board computer
to see if it will tell me if its a sensor.Ihave used a fuel cleaner.It seems to miss more when cold,but when sitting at stop sign you can feel it
miss every so often.Runs pretty good at high speeds above 10 miles an hour. this is 1993 4.6
northstar motor cad eldorado,150000 miles.

Answer
Hi Ted, If the engine hasn't had a tune-up in awhile that would be the first place to start especially if the spark plug wires have numbers on them that say what cylinder they are for which makes them originals from the factory. Be sure to remove the plugs a room temp and not a hot engine or you could strip the threads in the cylinder heads. If the plugs are originals too then useing some rust penetrant and letting them soak for awhile might be a good idea.
As far as useing the on board computor it is rather complicated and you have to know how to interpret the numbers that are shown. 1 day classes were given by GM to explain how to use the new diagnostics but if you press the off and warmer or off and red button on your climate control at the same time for 5 seconds with the key on or engine running then it will display the codes. At that point you will need to know if they are current or history codes, how to test them and how to clear them to see if they return. To do anything else will require a shop manual because navigating to the differant areas and tests the computor can do would be more than I can explain here. You could check your local library for the Caddy GM shop manual because sometimes they will have it. Otherwise if you can't get ahold of one then taking your car to a shop for diagnosis and the decide if you are up to replaceing the parts that are bad.
On a car that old and that many miles anything could be suspect includeing the fuel pump and injectors. And it might take a sharp tech to help figure it out. Bill