Hey guys, I got a buddy who's got a 93 Mazda MX6, 2.5L V6 5 speed, 180K. Has reduced fuel mileage, and sounds like its almost ticking under aceleration. Kinda sounds like its got too much advance, makes this noise from 1000-redline. Alos has a noise coming mostly from the back head, closest to the fuel rails. Hoping the valves aren't cooked, would like any help. Thanks in advance.