Misfire and hesitation problem

[lmpbzkt492]

Lately as the cold weather has been rolling in my car has been acting kinda weird. Its an intermittent problem with no clear pattern as to what makes it happen. Car will start up fine with no problems. Ill take it out and after driving for a while if i come to a stop the car will all of a sudden jerk and almost stall and from then on the car will miss at idle and hesitate and buck at low mph decel. It will do this until i shut the car off. then next time when i start it back it back up it will be hit or miss whether it does it again or not. it will not miss or hesitate under a load or at highway speeds just idle and low speeds. any ideas guys would be appreciated

 

[HISSIN50]

Have you pulled codes? That's a great example of an issue that might not illuminate the CEL but can toss a cookie in the KAM.

Also, if you're not stock, post up a list of year and mods.

Good luck.

 

[lmpbzkt492]

checked for codes and found nothing. car is pretty much close to stock. plugs and wires have about 25k on them and o2 sensors have about 5k. any ideas guys?

 

[jrichker]

Check the fuel pressure 37-39 PSI at idle, vacuum line disconnected and plugged. Then look for vacuum leaks.

See "Help me create the Surging Idle Checklist" at http://forums.stangnet.com/showthread.php?t=534062
for help with your idle problems. The first post contains all the updates to the fixes. I continue to update it as more people post fixes or ask questions.

 

[iLkYsPoNy]

Unplug the vacuum line from the EGR valve and plug it with a bolt. Drive it around and see what happens.

If it still does it... then I'm a dumbass.

 

[lmpbzkt492]

i do have a hissing noise coming from the brake booster area that i believe is from the booster itself leaking? would this cause my problem? wouldnt it happen all the time then?