Oscar a

Hi I 2008 mack mp8 with 650000 having problems with regen issues have no fault codes active for engine . Have new vgt actuator new egr valve check 7th injector is flow test found at 8lpm checked the diff pressure sensor check port found ok . Check the intake manifold pressure sensor found ok boost pressure sensor found ok. I perform regen on process the engine is start to surging at 12000 rpm the exhaust temp 1 is 300 temp 2 250 temp 3 220 any idea what this wrong