Failed Emissions...NOx & HC...any ideas?

OK went for inspection 3 weeks ago failed NOx 2.98 MAX is 2.00 HC 2.16 MAX 1.89 i think. Since then i changed the plugs(looked nasty), valve adjustment, changed O2 senser, and retarded the timing. Went again, NOx 2.47 and HC 2.06. So i asked the guy if spraying Carb. cleaner in the manifold would help, and he agreed. So do you guys think its a good idea, and do you have any other ideas i could try. By the way i have a ZC, and as some of you might know ther is no EGR valve. Going again this weekend so wish me luck.