Gas mileage has declined from 20+ on hwy to low 17s. Truck seems to bog down from dead start. Once rpms hit about 1500 seems to run fine. when idling in drive truck vibrates agood bit. Shift into park and vibration disappears.

 

What plugs and wires do you have on there? When's the last time you've changed them? About how many miles are on the truck?

A list of other mods might help too.

 

Factory plugs and wires. New plugs 5000 miles ago. 94k+ Miles. 2000 RCSB 5.3 Magnuson side mount super charger, gibson headers & catback exhaust, 1.85 rockers, shift kit.

 

I would try new plugs and wires. Sometimes if you have a bad wire, it can mess the plug up too.

Have you noticed any performance differences? If you have access to a scan tool, check your o2's to make sure they are updating quickly too. You might should replace the front o2's.

 

Seems to bog off line until about 1500 rpm then runs fine. No access to scan tool. Will check into o2s. Thanks for info Flyer.

 

That's still pretty good.

I'm with Flyer, I'd go for plugs and wires, next would be the aging O2's...

 

What plugs would you recommend for F.I. What is a good set of aftermarket wires.

 

i have a set of Taylor Thunder Volt 50's plug wires that i am selling. i paid over $70 for them. they have around 2000 miles on them and been in my truck since november. if you are interested i will sell them to you for $50 shipped.

my MPG has dropped too. must be because of the yank3000. i got it in the spring so this is my 1st winter with the TC. man the MPG suck now

 

doesnt NGK make a colder plug for F.I.?... or is that for nitrous?

 

Yes, NGK TR6 are one step colder for boosted/sprayed applications.
My milage has gone way south as well and I am leaning towards my O2s. On Atap, they switch really slow and are very inconsistant. When I filled up yesterday, I only got 13.1mpg from the previous tank.