No engine power
First thing I think of is clogged injectors. If you''re not getting enough fuel into the cylinders, you''re not going to get any power and you''re not going to be boosting rpm either. At idle, less excess fuel is showing up in the exhaust because there''s less fuel being pushed -- you''re in idle. Under load, with more fuel being sent in but not getting through properly, it''s showing up in the exhaust.
My $0.015 ( I don''t know enough to call it two cents.)