The sputtering and backfiring is the nature of the stage 1 cam. I thought I had a problem as well until I did some research over at the fordmall.
As for the surging idle...how is your air filter connected to the MAF? Try letting your car idle through an open MAF to see if it helps any. I had my K&N attatched right to the MAF sensor and what was happening was the opening in the filter was restricting airflow to the sample tube. All I had to do was cut out a larger hole in the K&N to allow more air to go through the tube and it smoothed the idle right on out.
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1989 LX 5.0 Coupe
13.30's @ 106.7 while doing the aod shuffle...needs gear and converter.
1992 LX 5.0 Convertible
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