1998Slow 'Stang

Car is a 98 GT. I put 1 new coil pack on last month 'cuz it was misfiring like all hell. Now in the past 2 weeks I've noticed a really really really really slight what I think to be a miss.

The car is kinda bogged feeling below ~2200ish (it is an NPI '98 I know, haha) then I get the slightest slight stutter of all slight stutters as soon as the tach hits 2200 and the exhaust note almost completely changes.

This is really noticeable in 4th and 5th gears when "lugging it". Also, on decel as soon as the tach hits 2200 the exhaust note changes, the car stutters a decent bit (enough to give a whiplash effect), and the engine braking effects comes on real strong, so to speak. The suspect coil pack was dropped during its process of switching cylinder banks.

If I'm way off in my analysis here, please, let me know. FWIW the fuel filter has less than 1K miles on it. Car was seafoamed twice, I run lucas or gumout cleaner/conditioner through it frequently and only use Hess, Shell or Rally gas (does it on all these). Also, at the recommendation of Cliffyk the IAC is new.

smokeystang

My 98 gt did same thing, I changed everything and went nuts, it is the cats plugging up. I guarantee it. I removed mine yesterday and piped it straight. Trust me, i went nuts trying to figure out problem. My car kicks *** now. Pulls through all rpm now. Let me know if this fixes yours. It don't take long to pipe it in, a lot louder and mean sounding. Let me know.

1998Slow 'Stang

Wow, I seriously NEVER would have even put that on a lit of relevant possibilities. Fortunately for me though, my car had an O/R H with weld in Flowmasters when I got it (it was done sloppy too, no rear o2 deletes they just put the factory ones back in....). Thank you for trying though man.

Any other thoughts......