Hi. My first time in the forum. I have twin 2007 Mercury 225 efi 2 strokes on a 33ft Donzi. Recently installed a new power block in one of the engines. Since the installation, cylinder 1,3 and 5 are not firing. Checked, there is current being supplied to the plugs. Engine stalls at idle. WOT rpm has reduced to 4200 only. Need help pls.