CODE PO304 WHAT IS CODE PO304, EVERYTHING RUNNS, IT DOES COME ON FLASHES THEN STAYS ON???

all misfires and bad mixture of fuel and air

https://www.google.com/search?q=05+TAURUS+CODE+SHOWING+po171+po174+po300+pO303+pO304

..

Sounds like you didn't quite get everything hooked back up. Double check that all the wires are connected.
what make/model/year? without that, the codes don't mean much.

The code PO304 means that cylinder 4 is misfiring and it could be that the sparkplug is bad and needs to be replaced or sometimes it could be the sparkplug wire

PO304.Code means there is a miss fire on cylinder #4. That is what they call a generic code for all manufacters, It mostly has to do with a bad Spark Plug or Spark Plug Wire on cylinder #4. Or it could also be the coil pack going For that cylinder, Depending on the mileledge on your car. End if it is (Abuse)

the P0304 means Cylinder 4 Misfire Detected
______________
om580 code reader

PO304 --is a misfire on cylinder # 4
The 171 is an O2 code from the misfire

Care to say what vehicle you have!

this may or may not help.
i have a 98 F150 with a 4.6 that i had an independent garage change the plugs and coil packs after i had the same problems you did. i had to take it back to him several times after and it never ran correctly, out of frustration i called the dealer where i bought the truck and took it to them. this was a small dealer about 200 miles from where i live, but my family is there. no large dealer ****, just leave the truck with us. one week later i got it back with everything fixed and it has run flawlessly since 2005. i was told that the problem was (1) the 1st guy didnt know what he was doing. (2) aftermarket parts didnt work. sounds like a load,but...

P0304 indicates misfire in the cylinders..
A misfire can be triggered by several situations. inadequate fuel, ignition misfire, insufficient air flow, too much fuel, incomplete compression... If you look at freeze frame data with a scanner you can see what the conditions were when the code was set, this will really help to pinpoint the problem.

the code is normally the air feed from the turbo intercooler to the inlet manifold, leaking, or the wastegate on the turbo sticking

ck if you have spark at the coil for that cylinder. check the plug wire closely. if it has spark at the coil, then replace all the spark plug wires.