Hey so I got a 2004 L59 5.3 swapped into a 89 gmc c1500. I converted it to drive by cable and ordered a PCM that supports that as my PCM was drive by wire. I did a cam, intake, and long tube headers. I recently started it and it backfires like crazy at idle like a constant backfire. The driver side headers seem to heat up like normal but the passenger side stay cool. If I bring the RPM up to around 2000 the backfire goes away. It has not been tuned yet. I can’t find anything on the internet and this is my first time so I don’t want to take it to a tuner if there is an issue. I have been through PCM pin outs and have physically traced and ohmed the injector wires and coil wires and they all lead to the correct injector and correct bank for coil wires. I did get a ICT coil bracket and I did not remember what coil was on what side tho I just threw them on. I also cut the knock sensor wires to delete them but today I ordered new ones and I am going to hook them up. I didn’t know any better and someone told me I did not need them but again I do not wanna pay someone to tune it if there is an issue and i can’t find anyone else having this issue on the internet so I have to assume there is something wrong. I have gone through and confirmed everything is hooked up and plugged in. I did change the MAP sensor to a 2.5 bar one that would fit the Holley intake I have. I installed a new timing chain when I did the cam and I am positive that I lined the dots up. I have 50 psi of fuel pressure. I posted a video.