Ford Mustang Convertable 3.8 2004

It sounds more like the timing chain jumped a tooth or five. It is possible the fuel injection management module (or whatever GM calls them...) could have gone bad and is not providing sufficient voltage to the injectors.
One or two injectors wouldn't cause the problem you're describing. If they're all clogged, check for contaminants in the fuel system.

DOES YOUR CAR STALL OR DIE AT A COMPLETE STOP? SPUTTER FOR A SECOND OR TWO WHILE DRIVING, RPM GAGE PEG OUT THEN ENGINE SHUTS DOWN? YOU HAVE ANY MORE SYMTOMS?

sounds like a faulty tbi or the vechiale is in limp mode do a code check and look up code on yahoo

Try changing the map sensor it controls idle and it could affect your car like that...........

for the top, I would suggest to check the gears of the motor if they are still meshing perfectly with the entire system.  It could be a stuck up motor, to be sure you need to open it up.  For the transmission, you may want to check the fluids if it needs changing and also check on the solenoid if it needs some cleaning.

the tach uses the same fuse as the other gauges, so if the other gauges have no problem then the tach is defective, Ford does not really repair these we just replace them.

Does it idle fine? Sounds like a vacuum leak.

sounds like you have jumped a tooth on the timing if not timing out

check all vacuum lines and especially the one behind the throttle body to make sure none are off and also check the EGR valve and if it has not had a tune up in awhile check the coil pack over the spark plugs

first of all if you have over 60,000 miles the car is asking you for a tuneup but take it to auto zone and they will put it on the tested for free so you know what you are dealing with.