87 mr2 missfires on+off after 1hr running an idiles up an down randomly

Toyota mr2 4age engine check your plug wires for arcing or use a volt ohm check resistance on each wire 4000ohms-15000ohms OK connect a vacuum gauge make sure its high and steady 18-20 AFM (air flow meter) – misfiring, dying right after it starts, bad gas mileage TPS (Throttle position sensor) – idle surging, high idle, gas bad mileage Idle Speed Control Valve on the throttle body – usually causes high idle Throttle body – usually causes high idle Vacuum/ intake gasket leak – usually causes misfiring and engine cutting off Ignition timing – usually causes misfiring