Full parts list:
K&N filter
Intake Vortex Generator
Slick 50 oil treatment
E3 spark plugs
Magnets on the fuel line
"Power conditioner" in the cigarette lighter
Removed tailgate
Your basically saying because of broken or worn parts lambda was much less than 1. Ok, that's not surprising.
TBI is an old design that isn't as good as current designs, no doubt, but at a steady state rolling down the road it's not going be 5 mpg off.
Great post!
It takes a X amount of power to go a given speed. You might be able to squeeze out a little efficiency here and there, but does anyone believe GM would leave 5 mpg on the table when they could just run a different air filter or put a different spring in something? It's ridiculous.
It's probably ok on race gas. Run colder plugs and all the other tricks.
What PCM are you running? There are some free tools out there that you could use like PCM Hammer.
I don't know if this counts as maintenance, but I melted a set of jumper cables once. The jumper and the jumpee had opposite battery terminals and I wasn't paying attention. It went quick too.
I've been through this myself about 87 times. On the Tahoe what finally made the brake pedal firm was about 3 panic stops form 35ish MPH. On the project truck, we just bled and bled and bled. It was finally ok after weeks of that until the axle swap and then back to square one again. I don't...
So we crawled under there and got some measurements. The Engine and trans are pointing down 8 degrees. The driveshaft is pointing down 2 degrees. The pinion is pointing up 8 degrees.
This gives operating angles on the u-joints of 10 and 6 degrees which is way too much and unequal obviously...