Hi Bob .
Any chance you can get hold of a code reader or scan tool to
check for malfunction codes .
G16B is your engine
I would be more inclinde to say you have a fuel pressure issue but a EGR is also possible.
Fuel pressure should read 2.5 - 3.0bar .
You could first disconnect the MAF sensor and then start up your engine and see if your power has got better, if this is the case replace the MAF if not then check the pressure of the fuel ,if low replace the fuel pump .
All look good then you will need the scan tool to check for malfunction codes .
Not much more you can do with out the needed tools for a EOBD II system.
BUT before jumping the gun when was the last engine tune up like plugs and ignitionchecked and replaced where needed.
If you have the tools just for peach of mind have the engine compression tested .
You should have a round 12bars on a good engine and not less than 8bars all four should not have more difference than 5% between each cylinder.
If all looks good then get back to me with malfunction codes .
If you need further assistance with this issue then please let me, get back to me with the reply button and not the poor or bad service, this way i can get back to you or suggest another expert if needed.
Kind regards Greg