I have a early 99 with 280,xxx with a 6 speed manual. Has 4 inch from turbo back ebpv deleted rebuilt turbo new up pipes and an edge programmer. My issue is that I be lost tons of power and am getting horrible fuel milage. Like 6-8 mpg bad. I don’t notice any smoke of any type. It starts fine cold or hot. It won’t build over 12 pounds of boost. Injectors are factory. Any one have any ideas.