94 Corolla intermittent stalls

Have a 94 Toyota corolla with a 1.8l Engine. I decided to be good to my daughter and tune her car, since the mechanic wanted $600 for cap rotor plugs and wires. I put the parts in and now it does a neat trick. As you are driving down the road the engine check light comes on for less than a second, the engine is in a stall condition. If it occurs at a light the engine dies, and must be restarted. THe engine always starts and runs fairly well. Yesterday I replaced the wires and looked under the cap to ensure nothing mechanical was happening. It ran fine till she got about 20 miles down the road and it did it a couple times, then in her town it died at the light and "popped" about 3 more times. For doing a simple parts replace this is beginning to get expensive, two mechanics have looked at it and cant figure it out. One removed the condenser in the distributor and that helped for about a mile.

Any ideas.

If I still had the old parts I would put them back in.

One more thing we cleaned the battery cables, replaced air filter and PCV valve, and replaced a leaking valve cover gasket. The wire to the alternator was over the valve cover gasket and it got a little stretched but not broke. The distributor cap is a little unusual as it has 5mm wires and a clip to hold the wires in and no coil wire.

THanks.