Error Code 172 & 175 & 300

[dangerous]

The test results indicated codes 172, 175 and 300.

172 and 175 are rich indicators for the left and right banks. Error code 300 is a misfire. But how do I move forward from here - The EGR is $135 and 4 Os sensors at $85+ each are not trial and error items to replacedue to costs. SHould I get some BG 44k and run it or is this an actual mechanical/electrical device that is bad.

The symptoms are that the suburban runs rough at idle. Otherwise it seems to run fine. the check engine lights comes on from time to time.
1999 Suburban - 120k miles, has had a new computer at 80k, new sensors somehwre down the way. I recall changing the fuel filter under the driver side chasis ast year. +-

Thanks!

[amac209]

have you changed the sparkplugs yet? also check the fuel pressure sounds like the regulator might be leaking and the plugs are fouled. check the throttle body for deposits too. my money's on the regulator. make sure the air filter's in good shape too. good luck

[dangerous]

I did replace the plugs - but will follow your advice and respond back - thanks - it may be the weekend though