Misfireing At 2000 Rpm

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Got a 99 GT, had a problem with a high speed misfire , replaced coil packs and plugs. When you rev it up it goes smooth until 1800 picks up a miss all the way up to 2500 were its really shaking the car. No codes or MIL light but code reader reads pending ING coil F circuit malfunction. Replaced that coli with another and no change in the way it runs.. Checked power to coil and pulse from PCM both good what else could it be??

 

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?????

 

[rdwelch]

Might ask this question at mustangevolution.com under the new edge section. There is much more activity there on questions like this.