I bought my 'burb in Loveland. I didn't think they were still so strict with emissions? My truck was originally "high altitude emissions" equipped, which AFAIK was something only sold for people in parts of CO (and wherever 85 octane is sold, which like I said I thought was just the CO). Maybe even Cali emissions were not tight enough for your specific test station? Weird because my father has lived in in Loveland for nearly 20 years (Mariana Butte) and I didn't recall him making a big deal out of emissions, he's got some old BS and I really doubt it's all tip-top, I thought you guys were a little more lenient with emissions than some other parts of the state (as long as you don't fart 2mph over the speed limit while driving down Eisenhower lol, maybe the hydrocarbons coming out my ass make a ticket worthy infarction)? In my state my truck is exempt, but if you need any high altitude parts I'm pretty sure I saved almost everything I stripped off. Let me know
Otherwise, I've had good luck in the past (in other states where they're less crazy) getting it good and hot so the cat is cooking like cray. Show up with like a half gallon of fuel still in the tank basically empty, throw in a good half gallon of high percentage rubbing alcohol to dilute it, and let them test away. It might not run great, but alcohol burns pretty darn clean. As soon as you leave, just fill up with real gas again and carry on with life. IDK what your specific ailment it, but I never bothered fixing it just preffered cheating the silly system that shouldn't be there in the first place...