Hi, its bob... please someone help...my E51 won't move uphill, changed plugs, fully serviced the engine, closed the exhaust leakage but no change, someone pliz help

If check engine light is on, have error codes read. I would suspect a bad or failed MAF or EGR valve.You can buy some MAF cleaner and try spraying it down. See if there's any improvement. If not, I would remove my EGR valve and spray the inside with throttle body cleaner.

What's MAF and EGR mean?

MAF CLEANER IS Formulated to clean and remove deposits within the Mass Air Flow Sensor. Restores power and performance, eliminating problems such as poor acceleration and reduced fuel economy. Safe to use on all MAF Sensor components and plastic housings.

Integral to the vehicle's engine management system, the aptly named exhaust gas recirculation valve, or EGR valve for short, recirculates finely metered quantities of exhaust gas to the engine intake system for increased engine efficiency, reduced fuel consumption and lower NOx emissions.