P1391 returned after replacing CMP and CKP and car shudders and backfires

Question

Had severe shudders above 3000 rpms and P1391 code. Got better for a while after replacing CMP and CKP. The code returned and the shudders are back worse than before and now every once in a while it shudders and I can here a muffled backfire.

Answer 1

P1391 Intermittent loss of CMP and CKP

If the code  condition was there before P1391 and still there the problem will not be the CMP and  CKP, Just be sure that when the CMP was installed the old rubber O-ring was removed and there was a paper gasket on the CMP to aid in the installation. You need to look at this a electrical problem either with the connection or the ECM. The best way to find the fault is with a scope or voltmeter and monitor it signal circuit. and  wiggle the wire of its connection and viewing for any abrupt changes dealing with the CMP as the most likely suspect..