Ok car runs good cold no issues at all but once it starts warming up the issue arises. It'll start sputtering and feel like its skipping with moderate or hard throttle, WOT and runs ok with easy driving. It also gives that light thumping noise when its sputtering if you know what I mean and it often gives off a wierd smell when the issue arises. The only thing I have done to the car as of right now is catless xpipe and slp cat back, no check engine codes, and it has 93k miles. This issue was never there before or after exhuast that I can recall, but one day out of no where my car started missing really bad to the point almost impossible to drive. That turned out to be spark plugs so I changed all spark plugs (about 4 months ago) and ran fine actually really good best it has ever ran since I've gotten it. Hard to recall how long after changing plugs this issue started I wanna say it started real subtle a week or 2 after and just kept getting worse. I should mention when i changed the plugs when i removed 2 coils the boots came off but i just popped them back on figured it wasnt an issue but who knows at this point. My car also burns a little oil time to time from worn valve seals but found that is pretty common with these cars and shouldnt cause issues. One more thing to add when I rev the car in park it revs fine with no misses that I can feel and idles fine and starts up cold fine but sometimes if I drive it like 20 miles once it gets warmed up and i shut it off and go back to start it up while warm sometimes itll hesitate to start sometimes taking 2 tries turning it over. Anyone have any idea or dealt with this to put me to the right direction before I start digging into it

 

Sorry for such a long description just wanted to add every bit of detail I could remember to get good advice.