If your pinging stops with some octane booster than I would should suggest, drainging your EEC. Disconnect your negative cable from the batter. Wait for the light onthe hood to dim out, and then leave the driver's door open for 3 min. Reconnect the cable. It might run rough for a while, but thats because the EEC needs to relearn its adaptive stategy. If it still runs lean after a couple days, let us know.
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'94 Cobra
308ci, ported GT-40 heads, Crane 2031 cam .513"/.529" lift 276°/282° duration, 70mm TB, Custom 80mm MAF, JMS chip, Vortech S-trim 8#, MSD, TREX fuel pump, Accel coil, 3.55's, FMS 1 5/8 headers, BBK Offroad H-pipe, and 2-chamber flows.
1994 Mustang Cobra
Check out the pics of my Motor Buildup!