so this would be my first problem with the car since the day i bought it, 5 years ago. a few months ago i switched my tune from 93 back to the 87 octane. car was running fine. now a few weeks ago it started running like total garbage. when idling, the car begins to rumble a shake slightly. the rpm's do not bounce, it just feels like the car is 25 years old all of a sudden (i just hit 50k miles). i was just driving to wendys (running crappy) and on my way back the car seemed to struggle to accelerate, my mpg according to the info button is 6mpg!!! the car is sluggish and feels like its struggling to breath. i havent cleaned the air filter in a while but it just doesnt seem THAT DIRTY for this to happen. any ideas? this all happened to fast. i also thought maybe it was because of the regular gas so i switched back to the 93octane tune and filled her up with BP gas...not much difference. any help would be GREATLY appreciated. all my mods are below incase the thought of a bad install would be the culprit

 

Clean your MAF and your throttle body. Also verify you have not leaks around the MAF or anywhere in your intake. Sounds like a air flow / MAF issue to me.

-danny

 

Agreed. But first I'd try disconnecting the battery to reset the ECU and see if that helps. Remember the idle learning steps.

 

I would go back to the 93 tune and see if it clears up. Are there any codes in the PCM or is the check engine light on?

 

I agree, sounds like a airflow/maf issue- Fords MAF is really close to the filter, if the filter aint seated properly it will really screw them up...we had a old van at work that wouldnt run, buddy changed out a ton of stuff(including the starter they burned up messing with it), I happened to walk by that afternoon, noticed the aircleaner lid didnt look seated right- opened it up, the gasket had a crease, was letting air pass around one edge just a little- apparently, if theres a leak, the swirling instead of straight airflow becomes unreadable- we just seated the filter and it ran perfect. I guess those weird shaped airbox lids are for a reason

if you might have ever ran over anything in the past year or two, might want to look for a dent in a cat too- I dinged one when I took our 85 camaro up a pretty nasty mountain road in colorado, dragged slightly just a couple times, looked it over before we headed back to ohio, just a tiny dent in the cat...a year later the cat plugged up- when I pulled it off, found the dent chipped the front 'brick' and the chipped piece musta rattled around till it completely plugged the 'brick' behind it's little honeycomb holes solid in the front- the car went from running fine, to down on power, to towtruck in just a period of days. a plugged cat should sound funny at the tailpipes, even with a crossover, one side should sound kinda quiet if revved

 

i do this every time...i ask the question and THEN search for the answer hahaha. it was the throttle body after all. drove to my local auto parts store, picked up some throttle body cleaner and got to work. took that sucker off and OH MY GOD was it gunked up! almost felt like the car was going to stall on the way over to and back from the parts store btw. but when i fired her up after cleaning it all out, WOW what a difference. it feels like a brand new car again!!! doesnt shake, doesnt hesitate when i hit the gas, a whole different beast. honestly, it feels like the day i got the tune installed, i was smiling so much i did a few donuts on the corner up from my house hahahaha. thanks everyone for the help, can always count on TMS!