[brooster]

Not all trucks are equipped with ESC/Knock Sensor Module, even though the book shows it in the picture. Extremely rare for one to go bad.

I'm assuming you have either a 5.0 VIN code H or a 5.7 VIN code K. VIN code refers to the 8th digit in the serial number. The Mitchell component locater manual shows the ESC on the right (passenger) of the engine between the throttle body and valve cover for 91 and 92 models. A Knock Sensor Module is listed for 93 to 95 models with manual transmission, but no location is shown.

According to another locater I have, it lists a Knock Sensor Module for 93 if it has a 5.0 and manual transmission; or 5.7 with either trans.

When there is no module, the knock sensor feeds the information directly to the ECM and the ECM makes corrections for timing directly.

Causes of poor fuel economy include but are not limited to:

State of tune:

Worn plugs
Weak coil
Low compression
Low/high fuel press
Improper timing

Fuel system problems:

Low/high fuel pressure
Restricted fuel filter
Running rich/lean
MAP sensor problems
Defective coolant sensor
Fuel pressure regulator sticking
O2 not allowing ECM to enter closed loop
EGR bleeding by
Vacuum leaks
Fuel leaks

Coolant system problems:

Thermostat missing/stuck open
Defective coolant sensor