seems like it
i just went around the block i will no more as the week goes by really hoping to see the fuel economy go back up was getting 15.5-16 now its at 14.5

 

OK BITCHES
16.1 so far!!!

 

mine has irridiums stock. they say ngk//delco on them.

 

FF in tank just saves GM money,I guess.

My truck was getting 18.5 combined but dropped to 17.5 about a year ago. I ran a can of Sea Foam through the gas last week. I haven't check my mpg lately.

 

My cc gets between 13.5 and 15 in town. On the highway, I get 18-23, depending on hills, flat, etc. I switched to a K&N drop in filter and no change. Only thing I ve done to the truck is the filter and put flowmaster muffler, 2 pipes coming out of it. I wish I could get 16 in town. BTW truck is at 29k miles.

 

oops just read that the air cleaner fixed you up- anyway straight from gm service information....


"Iridium and Platinum tipped spark plugs are designed to operate under normal vehicle operating conditions for up to 100,000 miles (160,000 kilometers) without periodic maintenance. As stated in the owner's manual, maintenance needs may vary because of all the different ways people use their vehicles. As a result, more frequent inspections and replacements may be needed if the vehicle is operated in extreme conditions.

When no engine performance concerns are present, Iridium and Platinum tipped spark plugs should not be removed for periodic inspection and cleaning of threads, doing so may compromise the spark plug's ability to withstand their corrosive environment. The threaded area, although not sealed, serves as a protective environment against most harmful elements. Removing and cleaning spark plugs will introduce metallic debris and brush scrapings into the thread area which may further the corrosion process. "

 

well after a tank of gas or two i now still show 14.5 has anyone ever noticed a decrease in mpg thanks
Ed