Is it a 4 - 7 swap cam? ( I'm not sure if hyd cam 4-7 swaps are avail
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This may sound stupid, but do you have a chip or some other kind of rev limiter on it? Chips do go bad. If you do have a chip change it or if it's a dial make sure it is well above 5,400. I run my limiter at 8,500 eventhough I only turn 7,800 to 8,000.
It also could be in the distributor. Are you sure the rotor is phased correctly and it's not cross firing?