I bought a salvaged 2013 mustang gt wrecked in front, minor damage with (110,000k) It had a BBK long tube headers with 3 inch x pipe and welded back pipes and roush exhaust. The code 304 had been there. I am a mechanic who has done a lot of rebuilds on other mustangs. I have an IDS non-commercial VMCII with laptop. Code p 0304, cannot eliminate it no matter what I have done. Ford said I need new long block $. I have taken the motor out and sent heads to machine shop, result: heads reworked no ridge on cylinder. all bearings good. re-ring the block, new head gaskets, ARP bolts, new coils , new injectors, new spark plugs, changed wiring harness, changed O2 sensors, relearn neutral profile correction with IDS. Checked PCM with computer (all modules passed).Compression is 160, fuel pressure 55, vacuum 52, leak down at 12psi on first gauge, 2% on second. Need help, code doesn't go away. Power balance -29 shifting in cylinder 4. Exhaust was changed back to original using Eastman cats and stock mufflers. changed the lifters and followers because it was apart. Any help would be good. thank you ED. P.S. New user to the IDS system.

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