2005 GMC Envoy Engine Pickup and performance lags

Engine Performance problem
2005 GMC Envoy 6 cyl All Wheel Drive Automatic 75K miles

Hi,

For the past 3 months my car has lost its usual pickup. Last month, I changed the oil, oil filter, air filter, but still to no avail there is lag when i push the gas.

However a little improvement was felt when I refilled my gas tank along with these performance solution ( to clearn carburetor engine system etc. ). Once a mechanic told me there is some dirt on spark plugs. though i changed the plugs like only 4 months ago.

I have to travel long distance next week, and am worried about the engine performance.

Any help would be appreciated.

Regards,
Sameh