my 92 civic Dx (D15 non vtec) with a D16Z6 swap does not goes more than 6000 rpms with a p28 chipped, im using the d15 wiring harness and the d15 intake manifold. the vtec selenoid is wired directly to the ecu. when i put new Valve Stem Seals i mixed all the valve springs (intake and exhaust) you think thats the problem? or im doing something else wrong?