help !

[BonnyLover]

Ok ! 2001 bonny ssei with 125000 km . Its doing that chugging thing when under load , slight up hill ect ect . I've taken some of your advises and changed plugs & wires , ICM & coils , mass air flow sensor , egr valve , pvc , tranny flush filter & additive , supercharger oil change , air filter . Still doing it so I took it to a friends garage were they plugged it in and checked the fuel pressure vacuum leaks ect ect and what they found code saying miss fire on cylinder five , then random miss fire . I was told maybe an injector but they unplugged it and the engine dropped so its working . they said maybe the manifold gasket has an air leak but not sure .... Any ideas or suggestions I should try would be greatly appreciated . The place I took it to was a Volvo specialist . If I take it to GM would it be better ?? $100 per hour and will they know any better ??
Thanks for any help you guys can provide.

[crash93ssei]

Try a new plug for cylinder 5. Even though you just replaced them, they can be bad right out of the box.