Emission Control problems of the 2007 Chevrolet Tahoe

My 2007 Chevrolet Tahoe will sporadically display two m. I. L. 's - service traction control and service stabilitrak. I have spent close to $4,000 on different parts, as well as having the heads completely rebuilt about 5 months ago. The only trouble codes it shows when hooked to a scanner are a p0300 (generic misfire detected) p0301 (misfire cylinder 1) and 0443 (evap emission control system valve circuit). After several months of research online, it is blatantly obvious that there are several thousand people experiencing the exact same issues. It appears there is no direct surefire resolution. But rather a common occurrence that is sometimes very labor intensive and extremely invasive to track down the specific problem. I have replaced the brake light control switch, added a secondary backup battery as well as additional positive and negative cables, replace the plugs, plug wires and ignition coil packs. It seems to be a recurring issue and at this point I have as much money invested in repairing the vehicle as I have spent purchasing it. I am not the type of person to sell this truck and let's have the misfortune of dealing with such issues but after several thousand dollars spent and discovering that it is a very common problem amongst Chevrolet / gm suvs and trucks, particularly with the 5. 3 l engine, I feel general motors should at least cover the expense of repairing it or let me trade it in towards a newer model with a sufficient credit applied. The issues I'm experiencing seem to happen when I am stopping or accelerating above 40 miles per hour. If I am simply cruising along at 25 miles per hour steadily and not accelerating or breaking, it doesn't seem to be as prevalent. But as previously stated, it is sporadic and continues to reoccur incessantly.