Is it possible my valves need to be loose

If it was tuned when the valves were out of adjustment it is possible the jetting is off now that they are opening like they were designed to be. Depending on how far out of spec they were you just gave it a better intake and better exhaust. More air going through the motor requires more fuel. Unless this quad is all stock and has factory jetting. If thats the case i would bet the carb isnt all the way clean or is just spent and needs replaced. I have personally had to keep cleaning a carb over and over to eventually get it unclogged. I even had it sonicleaned and it still wasnt all the way clean yet.