Reduce power engine ! White smoke

[Holden]

hi all ,,,

I am working on chevy Tahoe ltz 5.3 /2010 .. 100,000 KM only .


the problem is reduce power engine ! white smoke ! smell a gas !

I put my scanner and there is codes :

p2178 system too rich

p0087 fuel rail regulator and p0089 ( low and high pressure codes )

random misfire AND CYLNDER1 and 2 a high misfire detected p0301 and p0305 and one code for injection 1 leaking p029D ,, the car is too heavy and poor fuel economy

I just replace the spark plugs ..

any help ! I just stop the car now