1995 Pontiac Firebird computer?

I recently replaced the distributor and water pump. That was after I took it to a shop and was charged $558.00 to have the plug wires changed. The distributor and water pump I changed myself because 2 weeks after the wires were changed I took the car on the freeway for about 10 miles and the car started to run as bad as it did before I changed the wires.I took the car to another shop and they told me one of the wires had grounded out on the exhaust manifold. They also changed the plugs that had been changed when I first changed the wires. The mechanic made the statement that he thought that something with the computer might be going on as all the plugs seemed to be fuel fowled. They had only been on the car for about 2 weeks. Any ideas about what he could be talking about or any ideas on what I should check next?