i was looking on the forum and found one post on this with no replies so here goes...was driving home from work a couple days ago and my truck starting shuddering bad for a few seconds then would drive normally for a few seconds and repeat the cycle, i made it home and when my dad got home i ran our scanner and had an EGR code (forgot the number), both banks running lean (171 and 174) all three of which i havent been able to get rid of, but also had a po340 (Camshaft Position Sensor Circuit Malfunction) which was new... i bought a new camshaft position sensor and replaced the old one, the truck ran fine on the test drive a couple miles up the road and back but on the way to work today the truck started shuddering again in 2nd-4th gears (not in 1st or 5th that i could tell) but not to the extent they were before i ran the scanner again and its giving me the same code so any suggestions?

 

Ok, lets break this down. What engine do you have? What have you done in trying to fix the EGR code and the P0171 and P0174?

 

i have a 4.2L V6 and as far as the EGR i have replaced it, the EGR Feedback Sensor and attempted cleaning out the EGR to Manifold tube and still have the code(i have also check for vacuum leaks and cant find any). My biggest concern right now is the PO340, I dont kno if i need to replace the whole synchronizer assembly or if its my ECM of what

 

The 340 code is the PCM not seeing the signal from the sensor.
No syncronizer involved.
The sensor, the connector, the cable or the connector at the PCM can be at fault.
In addition, the cmp tells the PCM when to fire injectors and needs to be set in place correctly.
The 171/174 codes are the result of the same fault.
There is excess air getting in at some point in the intake system or the injection is being upset making the mixture to lean (the 340 code may be the indicator, as well).
Equipped with what these items mean, go looking for the cause.
Good luck.