Cold weather truck problems

[Faxcion]

Alright guys i started up my truck just a few min. ago and the CEL came on.. then a few seconds later it started blinking so i turned it off for a few min and then cranked it back over and the CEL stayed on steady. While all this was happening my idle was jumping all over the place it would stay at around 1500 then drop down to 500 and then try to die. I've had this problem before and the mechanic said it was my EGR valve needed to be cleaned out. Where the hell is this valve at? I've looked all over the intake manifold for it and haven't found jack!

Cleaned out MAF, Changed the oil before it got cold, checked all vacume lines, filled it up with antifreeze. Only other possibility is that its shitty gas??
Please help!

 

[OldCracker29]

What did you do the last time you had the problem? A bad TPS can do this also.

 

[Faxcion]

Was on my way back from work and it just lost all balls and went into safety mode so i had to creep it for 15 miles to the mechanics shop.

 

[OldCracker29]

Was on my way back from work and it just lost all balls and went into safety mode so i had to creep it for 15 miles to the mechanics shop.

What year is this, and do you have a code reader/scanner? This almost sounds like a throttle position sensor.

 

[Faxcion]

03 Sierra 5.3L
Its running ok now after i rodded the piss out of it just a min. ago but the CEL is still on and idle is steady at 500 but seems like every time i let it sit and then come back to get in it to go back to work it'll start acting up again till it gets warm

 

[CJ Hungus]

It would be nice to know what the codes were...

 

[Faxcion]

Where is the EGR valve located on my 5.3L?

 

[DV2000NJ]

Get the codes read BEFORE you touch anything else. Throwing parts at it without knowing what's wrong is just pointless.

 

[Faxcion]

Im not going to throw parts at it.. im going to clean it out, but here ya go.

P0300
P0174
P0171

 

[DV2000NJ]

P0300 = random/multiple misfire
P0174 = lean bank 2
P0171 = lean bank 1

You said it only does this once cold, not when warmed up, right?

The EGR goes from the passenger side exhaust manifold up to the intake manifold. I don't believe that would contribute to the lean codes, though.