My truck went from 20 mpg to 10 and is idling real rough I've replaced the computer and fuel injectors and put a new cadalac converter and oxygen sensors and still burning real rich anyone have any suggestions.

 

Did you replace all those parts hoping they might be the source of the problem?

1) Is the check engine light on (and if not, is it working)?
2) Check thoroughly for vacuum leaks.
3) What's the general maintenance history here? Last time for cam synchronizer replacement, plugs and wires, etc. Anything done right before the problems started?

 

As above for vacuum leaks.

There are two big vacuum ports, one for the PCV valve on the drivers side valve cover (that leads to a connection on the underside of the upper intake manifold, it's difficult to get to, check the line too) and the other for the EVAP system, it's located at the front (down low) on the upper intake manifold.
From that port, the vacuum line feeds into the EVAP solenoid on the inner fender well.

The other ports are at the back of the upper intake manifold, one for the brake booster (that usually doesn't give problems) and the other that runs the rest of the vacuum controls.
That one is split into a number of smaller lines for the EGR, dash controls and fuel dampener.

And about the fuel dampener, pull the vacuum line off of that, there should be no gasoline there, if there is, then the dampener has failed.
You can check the dampener with a cheap vacuum gauge, it will hold vacuum if it's healthy.

 

The guy i had bought it off of was the one replaced all that and the master air flow sensor. The check engine light is on and I hooked it up and the codes are PO102 and PO135 and PO141 and PO155 and P1132 and P1152 and PO122 and PO401. Thanks for your reply

 

If you have a manual you can look up those codes _ some are not in there, so Google the rest of them.

 

Wow that is a lot of codes. I pulled your info into the basic categories.

P0102 Mass Air Flow MAF Circuit Low
P0135 Oxygen O2 Sensor Heater Circuit Malfunction
P0141 O2 Sensor Heater Circuit Malfunction
P0155 O2 Sensor Heater Circuit Malfunction (B2S1)
P1132 FORD - Lack of Upstream Heated Oxygen Sensor Switch Sensor Indicates Rich Bank 1
P1152 FORD - Lack of Upstream Heated Oxygen Sensor Switch Sensor Indicates Rich Bank 2
P0122 FORD - Throttle/Pedal Position Sensor 'A' Circuit Low Input
P0401 FORD - Exhaust Gas Recirculation Flow Insufficient Detected

Read more: https://www.autocodes.com

I would first change out the EGR Vacuum Modulator Valve and make sure the hose is not clogged. Then clear all codes and run the truck to see what pops up next. You will probably get most of the codes back and I would look at the crank sensor next as it can thoroughly confuse the computer and cause most of the codes you are getting.

 

Very unlikely it's the crank sensor, they either fail or they work. If it failed, then the truck wouldn't run at all.
Checking and cleaning the connections can be done as a maintenance procedure, just to be sure they're OK though.

If you're still running the metal DPFE sensor, then replace it with the plastic one.
The metal ones corroede internally and can cause problems like you're having.

Here's a tutorial on how to check your TPS

http://easyautodiagnostics.com/ford/...imeter-tests-1

 

Thanks for doing the codes Tsquare

P0141 O2 Sensor Heater Circuit Malfunction
P0155 O2 Sensor Heater Circuit Malfunction

You have a blown O2 heater fuse or burned wires, or both

And could be general wiring harness issue because of all the codes, look closely at engine wiring connector, pull it apart and check for water intrusion or corrosion.
Check over main harness and look for damage, critters like to munch on wiring
All the codes could be caused by bad wiring, they have one thing in common, low voltage, and low voltage can mean no voltage in computerese, so broken wire

You are dumping gasoline into the engine or you are leaking it if 10MPG is accurate
If you don't smell gasoline then it is going into the engine

You need to do the Clear Flooded Engine test
Cold engine
Turn key on(RUN)
Press gas pedal down to the floor all the way, HOLD IT DOWN
Try to start engine
It should NOT start, it should not even fire, the fuel injectors are turned off by the gas pedal being at Full Throttle

If it starts or fires then you have gasoline leaking in

All the fuel injectors get 12volts when key is on
Each injector has 1 wire that runs back to the computer, the GROUND wire, the computer grounds that 1 wire to open that 1 injector to let fuel into the engine
So what happens if that 1 wire shorts to Ground, yes, injector leaks fuel into the engine.
Again we are back to a wiring issue