Trying to figure out what my drop in MPG and rough idle could be.

Noticed a drop in gas mileage recently from 14.5-15 mpg on average to 13-13.5 mpg on average. Today after leaving work and driving for about 15 minutes I came to a stop waiting to get on the ferry. It was a bout a 25 minute wait and during this wait I noticed the truck had a slight rough idle. Once getting off the ferry and driving on the highway for around 20 minutes at 75 the rough idle went away. I also have noticed a slight hesitation sometimes when getting on the throttle as well as a long start. There are also no check engine codes.

Things I have done:
Cleaned MAF sensor
Cleaned TB and sensors
New filter and gasket material around the air box
Gotts intake mod
Fuel filter replacement
Regular oil changes with Mobile1 5w30
Spark plug change with Sp515's

Things I have not done that could possibly be the problem:
FPDM replacement (has some corrosion)
COP replacement (one looks to be after market)
Replacement of Cam Phasers and timing components (it has a tick)
Catalytic Converter replacement

Something else that I have noticed is that smoke comes out of the exhaust on startup.

During my drive today I had my OBDII reader plugged in and pulled this data off of it.



Accelerating





lifting off throttle





lifting off throttle

My Long Term Fuel Trim bank 1 sensor has been reading about 2-6% less on average than bank 2, which I thought was odd. Fuel pressure seems to stay between 37 and 40 psi and fluctuates accordingly.

 

Could be your O2 sensors going bad too. They control all the fuel trims under full throttle then the MAF takes over.

 

Good point. Didnt think about that. I will check for low voltage in the morning.

Maybe also an exhaust leak causing bad readings on the O2's?

 

sub'd

 

Following, been chasing a slight rough idle at a stop for a while with no luck

 

I think you'd have to have a pretty decent exhaust leak for that but depending on your current mileage on your truck they may need replacing. And that aftermarket coil could be a culprit too

 

I think I may have a leak at the passenger side manifold but not sure.

 

Might as well just change front o2's. While your down in that area....check the oil pressure.

 

At 115K I probably do need to change the O2's but I dont want to just throw money at this problem. I will replace maintenance items when I have more cash flow or when they show signs of failure. Right now I need to do as much troubleshooting and gain as accurate of a diagnoses as possible.
What is the oil pressure average for this truck?

 

Noticed a shutter when I let off the gas today.