Throttle issues/gas issues

[blkfleet]

hi folks,
i have a crazy problem here with my 08 tahoe 5.3l flex fuel truck. let me try to explain in detail.
first i was having throttling issues from dead stop and at times when i needed rapid acceleration. i also notice my AFM feature wasnt switching between v4 and v8. i also was getting general "misfire code"
so a friend told me to switch AFM plate out, i did and i kinda got alil kick back to the engine i could see the v4/v8 switching on my info screen. and that only lasted about 1 day now i am stuck in v8 mode. also if i filly gas tank up i can drive about 30 miles and my fuel gauge needle begins to drop! also i am getting a slight popping/puffing sound from the muffler. the truck still has a slight issue on quick goes from a dead stop. i know i just listed alot of stuff but i am lost and i love my truck not trying to give up on her just yet! any help sure will be appreciated here!!!! i am having to put $20 of gas just about every 2-3 days i commute 50 miles round trip per day, this is going to make me have to take out a loan or something...smh

 

[Doubeleive]

what is the mileage and when was the last time it had a tune up?

 

[blkfleet]

what is the mileage and when was the last time it had a tune up?

i do most of all the preventive maint. on the vehicle from fluid changes to brake changes, to performing flushes and what not. the truck has 125k on it. but to say taking it to the dealer of a shop for maint never have had the need to til now....lol

 

[Doubeleive]

I was just wondering when it last had plugs/wires changed, throttle body cleaned, mass airflow sensor cleaned, etc, that all has to be done routinely, as well as using a some injector cleaner regularly.

 

[swathdiver]

Where do you live Francisco? Maybe someone from here lives nearby and has a good scan tool to see how your motor is doing?

When you say AFM plate, do you mean the VLOM under the intake manifold? Did you also change the intake manifold gaskets?