well my yukon is up to about 94k now original plugs/wires (to my knowledge) change oil every 3000miles with 5w30 valvoline and k&n oil filter. my mods in sig but lately like the last month or two ive noticed it being much more sluggish even on the cool nights and my mileage has droped considerably to 12 with mixed driving where i was getting 15-16. ive got a new fuel filter i need to put on but i need the tool to do it. woul checking out my cats to see if they are getting clogged help? ive been debating on gutting them anyway. id rather wait for longtubes and ory but we are in the process of closing on a house so it will be awhile before i have extra money for mods so any more free/cheap mods repairs are the way to go lol. it feels like it needs to downshift more to get around than it used to and like i said just feels like its struggling.