It's a long shot, but it could be low flowing injectors, I would install
a Mixture Meter to see if it's running lean before pulling and changing
the injectors, or you could pull them and have them checked for flow.
You can do this yourself if you want to rig up a way to trigger the injectors
and measure the flow rate, also check the spray pattern, should be a good
cone spray, no flat spots on one side or squirting like a fire hose
Just a thought
Wild