Have been dealing with a stumbling problem for some time. Replaced wires, plugs, egr, rotor, distributor cap, fuel filter, cleaned EGR tubes, O2 sensor. Nothing helped so I took it to AUTO LAB for a diagnostic test because I was getting no codes on the OBD I. They got a bunch of codes all of a sudden when they warmed up the vehicle. They were 19, 16, 18, 15, 12, 24, 27, 26, 21, 23, 20, 48, 77. I am assuming all of them were starting with a "P" because of the electrical problem they said I had. They wrote down, 2 additional hours of diagnostic testing needed as it may be a bad ECM or a Bad harness. Cost per hour of diagnostic work $80.00 per hour. I can get a new AC Delco ECM for $77.00! Any suggestions would be greatfull!! This is an 89 Cadillac Deville with 4.5 litre, 74,000 miles!