hi, i was hoping someone could help with my 98 civic, its a 1.6 non-vtec motor and for some reason it wont rev behond idle. It's recently had a new engine fitted and ever since it hasnt rev'd behond 800rpm. I've checked the timing and it seems ok and compression is within the guidelines. When the thottle is fully wide open all that changes is the engine tone, and you can hear the valves popping as if air may be traveling back up the inlet manifold. Does anyboby have any ideas?