have a 2003 chevy trailblazer 4.2 v6 with codes po171 and po301 and po440
ok i just had the fuel pump replaced so i will take it back to the shop .... i did fix the misfire it was a bad coil
Try fixing the misfire and the running lean codes, that might fix it all. Often a weak fuel pump will cause the lean and misfires, pressure test the fuel pump FIRST. A weak pump can do all that.