3.8L V6, (from old 3.3l ) OHV ,push rod simple )
same car as one of mine, same engine, mine is 08
p0300 means all 6 cylinders fail or combustion pressure, weak.
at random.
so not 6 bad spark plugs news and gaped to speck
so is bad fuel?
so is 6 clogged injectors,, NO.
hot engine has normal idle rpm 800 or screams only.
yes that is called gross misfire and lost of engine power too you forgot to say.
got AF radiator water in the oil pan , looks like like chocolate milk?
mine has 100k runs like new, water pump only failure ever, 100k miles me.
seems like bad fuel to me. ,diesel put in to gasoline tank?
the only weakness this motor I know is 2.
1:lower manifold gasket leaks and AF coolant falls to top of engine and down.
replace coolant every 5years is win to avoid that.
2: egr failure sticking open and a pain to reach, unless right finder pulled fully
im sure compression tests pass at 150psi up. sure. 50k miles how can it fail.?
make sure at AM dead cold engine, rad cap off rad neck is 100% full of AF.
never let it drop, and keep side tank 1/2 full cold.
never forget to burp the coolant here as you replace it all
as you fill it up.(AF antifreeze coolant)
hose off here, heater)
fill rad until it leaks here
hose back
then fill rad full to top of neck.
https://drive.proton.me/urls/2AJBWHFE3R#n9DXuC8sIcOD
link is new pump installed steps PDF