Car Intermittently dies when I take it out of gear

Discussion in 'SN95 4.6L Mustang Tech' started by Timin, Jan 30, 2012.

  1. Hey All,

    I have a 98 GT 5spd that I don't put many miles on at this time, and it has been experiencing this issue for the better part of the past 3 years or so. Basically, I can be cruising around (usually under 50MPH) and if I take the car out of gear and put it in neutral the RPM's will not bottom out at the normal idle range(675-750 rpm,) and it will just keep going lower and the car will die. I can prevent this from happening if I tap the gas right as I pull it out of gear; the car will idly normally every time I do this. There are no other idling issues at any time while cranking the car cold, idling at lights, etc.. I had to replace the IAC many years ago and if I remember correctly the RPM's would hang around 1200 even when the car was stopped, so the symptoms seem a bit different.

    We replaced the plugs and wires at 90k miles (NGT TR55's,) and I had the unfortunate luxury of the #8 cylinder shooting the plug out within a few months. We ended up tapping and rethreading the existing head; I had a mechanic do this so I am not precisely sure on the current details of the plug in that cylinder (Size/Temp.) I set the timing back to the factory level 10 on the T/A, and I recently ran Sea Foam through the engine for the very first time. Neither of these have had any impact on this. I have not cleaned the MAF recently (not sure of the last time I did,) and I think this is something i'll take care of here this week. One last thing to note, when I look at my 2 Chambers it appears that I bought them with some piping already welded on to the muffler; this piping appears to be 2 1/4 or even 2 inch pipe. So the exhaust does bottle down some before it gets to the actual muffler, not sure if backpressure or anything else related could be a culprit?

    Mod details and other information:

    150,000 miles on the car
    MAC Long Tube Headers
    2.5 inch VRS High Flow X Pipe
    2 chamber Flowmasters
    Steeda Pullies/Timing Adjuster

    Thanks for any thoughts on this: