I bought a 1999 4.6 gt mustang used, drove it for about two months a month into driving the car i had missing so i replaced the coil on plugs with new oem ones all 8 ,ran great then parked it. the car sat for a month and a half when i went to start it the battery was dead so i took it out and charged it, when i put it back in, the car was hard to start some times i would have to turn it over 3 different times then turn the key all the way off and turn the key again 3 or 4 times, then it will start and idle, also misses every so often out the driver side pipe has dual flows, when i push on the pedal to fast the motor will die out but if i let off the pedal it will catch its self but if i keep my foot at a certain position after pushing the pedal to fast it will die. if i ease in to the pedal it will rev up to 6 grand. same thing if i get under the hood and move the throttle by hand. so a few days later i go to start the car but now it just turns over so i bought a new fuel pump from auto zone and installed it nothing really changed it starts now with same symptoms. i was able to drive the car for about 15 miles and reached speeds of 70 mph a couple of times, when i come to a stop, some times the car would die not always just out of no where. if i let the car idle for a min or two after just starting it and its cold the motor that is,it will die out of no where. when i let the car warm all the way up if it dies will not restart for at least ten min or more.. so i take the car to aamco since they're having free diagnostic computer read out they told me in order to tell me what part or parts i need they will have to do more diagnostic testing because there's twelve steps for each code and i have 4 codes that came up. here are the codes they gave me...P0190fuel rail pressure circuit fault, P0172 system too rich bank 1, P0175 system too rich bank 2, P0300 random misfire detected...does anybody know whats wrong?.... i looked at the sticky: tech articles and how to's. and could not come up with the online Ford repair manual, seems not to be working... lastly does any body know the name of this part in the picture, its the one on the fuel rail on the drivers side on top closer to the front of the motor with wires coming out of it and its square and black...

 

I'm here. Lol. Jk. Sounds like a vaccuum leak. Check all hoses and spray them where they connect with carb cleaner and look for bubbles. If so, vaccuum leak. If not, You also should check your o2 sensors and clean your maf sensor. Do this and report back.

 

It actually sounds fuel related and sound like your running lean. Check your fuel filter too because 9/10 it's probably never been changed.

 

not a vaccum leak i checked that 1st i also think its fuel related but i don't know the name of the part in the pic and i think i need a new one

 

looks like a fuel rail pressure sensor, but I'm not certain my car doesnt have one, but would make sense being on the rail and not looking like a regulator. On a side note it's probly just pissed off it's so dirty

 

Fuel pressure sensor. Check to see if vacuum line is not broken and functioning correctly. If ok, replace sensor. And make paragraphs as its really hard to get lost in a large paragraph.