Hope everyone enjoyed their autumn season. So here is where I am at now with this LS: -New coils and sparks were done, as mentioned in a previous post. New 02 sensor was done. Since then, I got this car taken to a different mechanic. Here's what we did. Hooked up his Snap-On scanner. *Compression checked, everything is great *Fuel Injectors checked, everything is solid there. *Checked the live graphs. Noticed that the PCM is adjusting mix ratio a fair bit on cylinder 6. He checked a whole bunch of stuff, everything looked great. No misfires on the live data. Now.. Left the car with the mechanic, and he opened up the throttle body. Found it was filthy, so he cleaned it. He also noticed the EGR valve was dirty. So he cleaned that as well. Rescanned my LS, and got misfire on Cylinder 7/4/1, but only once. (cylinder 6 is on best behavior now). Mechanic (with my permission) modified the intake. Opened up the bottom to allow more air through. Definitely noticed it, sounds nicer and car has more pull with Torries street tune. I went to pick up the car, took out for a ride in town. Upon start up, idles dropped very low. Got to a Stop sign, the idle dropped to below 600RPM, sounded like the car wanted to die. Did this a few times, until it warmed up, then idled properly. Let the car cool down. Didn't do it again (YAY?). Drove it home from town, no issues. Punched it on a side street, aaaaand F**k me - ETC Failsafe. NO OTHER CODE. Just failsafe. Only failsafe. Cause, why should I get another code? I dont deserve another code, just P2106. So Injectors check out. Compression checks out. All cylinders are firing. EGR valve cleaned. Throttle body Cleaned. Please, I'm literally at a dead end... I dont know what else to do. EDIT: NOV/22 The mechanic informed me the misfires were BEFORE he cleaned the throttle body, not after. He said he no longer shows misfires. And, the misfire was only once on those cylinders. Also, he said he cleared the cars parameters, which is why the RPM drops were there when I first started. He also cleaned the fuel injectors.