1989 Honda Prelude Runs on 2 cylinders.

After replacing the distributor cap and rotor the car ran fine for about five minutes (2 miles) and then started missing and wanted to die. It would not idle unless the throttle was kept slightly open. I checked the cap and rotor, wires and replaced the plugs (as they were fouled and 1 & 2 were wet). Everything checked out. The engine ran only on 2 clyinders (3 & 4) as I checked the plugs again (1 & 2 wet and 3 & 4 sooty). The "check engine" light did not go on and there are no codes on the ECU. Please advise.