And it has a miss. i Think. what did the problem end up being

 

it was muggy outside when it happened. let it sit over night, next day was nice and it cleared up. i have a cam/tune so not sure if that changes any of this for you

 

This code has been around since ive owned the car so weather isnt the issue, although it does idle high as hell when you first start it in cooler weather, like at around 1000 rpms.

 

Im starting to notice that everynow and then when the miss isnt there, the car idles around where i should. Could it be that it has a miss and the car is revving itself up to keep itself running?

 

After it started getting up into 80s here everyday, the code went away for a week, and just today it reappeared, but it really didnt get much cooler, just maybe by 5 to 10 degrees. Does this really change anything. Im really starting to think its being caused by the slp maf sensor, but i wont just throw a 500 dollar maf sensor on it just out of my own intuition. Anyone here have any other ideas?

 

#4 above is probably not correct. The HVAC vacuum system is connected all the time, and a leak anywhere from the manifold connection to the control panel will leak whether the HVAC is being used or not.

Have you checked the gasket between the TB and the manifold?

There should be a diagram of all the engine vacuum connections, on top of the radiator cover. You have not mentioned vacuum sources for the EGR and EVAP purge systems. Have you checked those? I'm not an LS1 expert... my knowledge is the LT1, but if the LS1 has those systems, there may be vacuum connections.

 

There is an airbox lid on the car and the diagram, i believe was on the old airbox baffles, which werent with the car when i bought it. I didnt even know about the evap, but next time i can get access to a shop, maybe next weekend, I'll check it out. Where would the egr system leak from, would it be the large hose that goes into the manifold? Other than that i dont see any other vacuum sources for it. Would a clogged evap can cause a restriction and set a high idle code the same way a pcv valve would?

 

Would something being wrong with the egr cause a little bit of a miss without throwing a code? i still havent been able to look at the evap canister but i think i can pretty much eliminate a bad ecm because the code consistently goes away when it warms up