Hello guys! Looking for some advice, I recently bought a 2014 Camaro 2ss straight drive the previous owner had cammed and tuned the car. I got it from the dealer ship test drove it and bought it with 20,000 original miles. It came to me and had some check engine light p0106 non MIL assuming it was tuned out as I know cars with big cams can tend to throw this code and put it into limp mode. I bought headers and a CAI and installed them to the car, took my car to a local tune shop (long time hp tuners but mostly familiar with Euro cars and I have also watched them tune several LS swapped classics) they are informative and super helpful. Found out the tune that was on the car when I bought it was blocky so not very smooth on the maps as well as super rich and -15 degrees of timing around 5500 rpms so with that tune the colder plugs and the hole behind the bumper we are to assume it was pro charged previously.
Now we tuned the car and it was running great but I started to have TB issues and going into limp mode well the TB that was on the car was ported, so when I replaced it with a stock TB it needed to be re tuned, and it ran ok for a few days and then its started to pulse randomly around 1500rpm cruising (actually always had this, I always assumed it was just part of having a large cam but its inconsistent and verys from 1k rpms to 2k), now getting lean and rich codes, tightened the parameters around the fueling and still swinging in and out of lean and rich, random back fires on deacceleration, and on take off will lug till it backfires then take off like no tomorrow. I havnt really had any WOT issues by the way (most of my issue has been low rpms like parking lots, stop and go traffic, ect). So I left it with my tuner for a few days and he turned on "air density" and lowered the maf control he test drove it and pulled it on the dyno, it made more power and everything seemed to be in working order, I get it back and it stalls when I get home like wont hold an idle restart it and it's fine. I go back after trying a new map sensor (assuming the code was really detecting a fault), really limited the maf to see if there was a vacuum leak so at this point we are just trying to see if there is a sensor working incorrectly so we have been limiting the computer to see if something changes due to not knowing what the previous owner had done. He thinks the map sensor is the culprit or a bad wire, possibly ecu. I'm thinking that although he may be a good tuner for Euro cars that maybe the GM stuff may have a few things he's overlooking, Or a few functions that he's unaware GM stuff does. So what do you suggest besides to get a better tuner? Is there a function we are overlooking? Are we making this harder then it is? I also know nothing about what has been done to the car, the more I dig in the more performance stuff I find the previous owner did spend lots of money on this car and looks to be pro work done to it.