Jim, reset the ecu and it should start showing some gain.If you have access to a scanner post the fuel trims and I can help more. You might have a vaccum leak or lazy o2s.
The groove enhances slight existing problems you wouldnt notice till grooved.
The scanner is a tool you need to get if your gonna do this as a business.The more you do the better youll get with the scanner to determine if any problems exist.
Need any more help feel free to call. Hope to see you in Carlsbad New Mexico Oct 12 and 13 for hho rally !!!!!!!
Dan Merrick Gadgetman Mo. Google T2 hho and check out the motorcycle running totally on Merrick Gas