GM Techs, trouble code help?

[Dragster Racer]

2001 Impala, 3.4, 271k miles, has had the intake gaskets done, but long ago.
Just replaced the radiator, and water pump and belt..leak and a bad pump. Had an underhood sqeak of the air box and sprayed silicone to lube the mounting bushings.

Not it idles terrrible with misfires and pops codes
po300 random misfire
po341 camshaft sensor
pending codes
po420 converter eff
p1404 egr

Now the SES light has been on forever with the egr one, and I was just saying how nice the car drives for the miles it has, and 28 mpg. I jinxed it. Now how do I fix it? Not sure where to start with diagnosis.
Help?

 

[GMCAMARO]

Start with the camshaft sensor, ensure the wires are complete and if they are replace the sensor. That should aid in the idle problem, probably wont solve it but it is the starting point.

 

[DiscoBerry]

generall rule of thumb is diagnose the lower codes first cuz they often set the higher ones as well but i too would agree this has somehing to do with the cam sensor

 

[79firebird]

cam sensor. had the same prob on a friends car. there is a chance it may not be but with k like that its a higher chance.

 

[rmsg0040]

why not try and clean the throttle body might help with the idle issues

 

[Milton Shaw]

I had a3.8 with cam sensor code. The cam sensor was not working because the magnet in the cam had fallen out. Had to tear down the front and to a timing chain job to get the magnet back in. What a load of work for a $5.00 part. I hope that is not your problem but after you replace the cam sensor if it doesn't work then bump engine over and look for the magnet.

 

[Dragster Racer]

Moved the wires to the cam sensor around, and took it for a drive. Runs perfect. I'm sure this will rear its ugly head again. At least I have a suspicious place to look.