98 Chevy c2500 5.7 check engine light and shudders when i turn right

Is the po300 the only code you are getting? You may want to check the fuel pressure, it should be 56 to 63 lbs. The po300 code possible causes are:- Faulty spark plug (s) - Faulty ignition coil (s) - Clogged or faulty fuel injector (s) - Intake air leak - Fuel injectors harness is open or shorted - Fuel Injectors circuit poor electrical connection - Ignition coils harness is open or shorted - Ignition coils circuit poor electrical connection - Insufficient cylinders compression - Incorrect fuel pressure... The P0300 code means that a cylinder(s) is misfiring or is randomly misfiring. Start by checking for intake leaks, intake gaskets are common caused of multi-cylinder misfiring. If no leak are found the next step is to replace the spark plugs. If the problem persist more tests needs to be done to diagnose problem,

yea that's the only code. would an exhaust gasket have anything to do with it. mine is just shredded to shit and ive been a lazy ass and rtv'd that bitch.

No the exhaust gasket would not have anything to do with it.

alright now its saying system too lean bank 1 and 2 along with the random cylinder misfire. but the check engine light isn't on. that thing turns on and off and random times. does that have any significance?

I would believe you have a leaking intake manifold gasket. These Vortec motors are common for that. You could try and take a spray bottle of water and spray along the intake gasket. There would some change in the rpm's indicating a leak. A lean condition is too much air. Then you could try snugging up the intake bolts, and what is weird on the torque on these is that they say to only go to 12 ft. pounds. I went to 20 ft. pounds on mine.

I had it diagnosed and they said the check valve was bad and the #6 injector was bad so I changed the injectors to mutli port fuel injectors. they also said the check valve on the pump was faulty. Could this be an underlying cause to the mulitpe cylinder misfire

" Could this be an underlying cause to the mulitpe cylinder misfire" Yes, it very well could be. Have the codes cleared so IF the check engine light comes back on, the code (s) would be fresh so to speak.

yea they cleared for about 30 miles along with the shuddering when I turned right. after that the light came back on and the shuddering began again but not as bad this time