under medium to hard acceleration in 3rd, 4th and 5th gear i get a bad bogging/skipping kinda thing going on, but i'm not throwing a code. i just had the plugs and wires changed about 3-4 months ago. my mechanic checked the fuel system, it's ok. i've cleaned the maf and it looks fine. this has been a persistant problem for a while now and it's starting to get worse. i've also run fuel system cleaners. it's a 2003 mazdaspeed protege with 100k on it. my mechanic thinks it's the plugs, but this will be the 3rd set in less than 15k when he puts them in later this week.