Well, I bought my 98 GT about 4 months ago from a good friend of mine...since then, I have added BBK Long Tube Headers, BBK O/R H-pipe, and a Flowmaster 40-Series American Thunder Cat-Back...Thaty's the extent of the work at the moment because I"m in Iraq and I"m not there to install anything, and I'm not real big on anyone else messing with my car...lol..I like to do the work myself...The car has about 139000 miles on it...It's been mis-firing and I can't find it..I have replaced the intake gasket, changed the plugs and plug wires and it's still missing...Does anyone know what could be causing it?...Also, right before I left to come over here, it began to knock, which is never a good sign I know... ...So my question to everyone is, do I ditch the motor and go with a new one?...If so, where is the best place to get one from?...I"m new to the Mustang Family and looking for some help, It took me a long time to get this car...It's my pride and joy...Any help would be greatly appreciated...Thanks for reading....Bryan  

hello, this is greg.
i just subscribed to this site, and have a 99 gt that is acting crazy too.
email me at
gregoryteet@webtv.net and maybe we can find out what's going on with the cars together.
just because the car is knocking,i  have been told that it may not be reason to replace the engine. i have replaced my fuel fiter,checked the coil packs,and now have a stock cat system in place to replace the cats to see if the cats are stopped up. i have also been told it may be the computer or the mass air flo sensor. man i don't know what is wrong. somebody out there give us some sugestions please.
thanks
greg  

I hosed of my 96 GT engine last fall and the engine started knocking too.  The engine would fall on it's face after driving it 500'.   I thought I warped a head or something.   This spring it started and has been running fine all summer.   At the time I changed the plugs and WD'd everything I could think of to no avail.  The engine knocked so bad I thought I was going to have to replace it, glad whatever it was dried out.  I never figured it out,  Anyone else?
-Scott  

With that many miles I would suggest looking for a low mileage PI Motor ('99 and newer) It will make a huge difference in the smile you have when you get on the gas.  

i am not very familiar with the 4.6 motors but it sounds like mabey a timing sensor of some sort. mabey the knocking you are hearing is detonation caused by the timing being off. im not sure how the do the timing on those motors but if they use a sensor triggered by the crank for the ignition timing mabey that could be it?  

FIRST OFF CHECK YOUR FUEL PUMP.  99% OF THE TIME ITS SOMETHING STUPID LIKE THAT.