Engine idle is surging up and down and won't stay running very long. Replaced IAC, fuel pump assembly, cap &rotor, plugs,and wires. Not giving any codes. Smell fumes, not gas but fumes( light fumes not over powering). As soon as I step on peddle, stalls out. Sometimes starts right up , sometimes cranks awhile. At end of my rope. Can anyone offer their input. 1999 Dodge Ram van 3500 5.9 liter gas engine

 

Do you have a steady vacuum reading holding around 20-22?

 

Don't know how to check vac reading. Guess can find a vid on YouTube

 

Perhaps you have a plugged catalytic converter.
Steve

 

Cat is emptied out. O2 sensor (down stream) has fouler on it. Even took muffler off.

 

Get a BASX OBDII Bluetooth enabled reader and the computer will tell you using the Torque app.

What alloro said was my first thought too.

 

Can they be rented from Advance Auto ect

 

I don't think so. It is actually BAFX.

https://www.amazon.com/BAFX-Products...words=basx+obd

 

Might want to make sure you have good fuel pressure even though you replaced the pump. May be an issue with the relay.

 

My 95' 3.9 started having power steering problems. Turning would work half way normal and then tense up. It has also began running with a hickup as I coast down the highway. A few backfires have occurred as well.

I have replaced the computer, replaced and checked wires/plugs/cap connections, checked vacuum lines, used diff fuel, cleaned air filter. The valves sound normal.

I am thinking that my brake booster is failing. HOW DO I MEASURE the vacuum pressure???