I have an 96 B250 with 120K miles and the 5.9 engine. The van will start and idle fine, but when it's being driven it will die when I let up on the accelerator. It is also prone to die when shifting between park, reverse, and drive. I have cleaned the IAC as described on this site but the problem persists. The van will start right back up without hesitation.

Any suggestions?

 

Since cleaning the IAC didn't work, you might just have to replace it.

 

Since the IAC is clean, other items to note are ...

- Replace the cap-n-rotor with a copper/brass type.
- Replace the spark plugs with Autolite AP5224 platinum plugs.
- The ignition wires, if original need to be replaced. Make sure to use the same size wires. This is 7-8mm in size. 8mm would be best.
- Have the coil checked out too. With the mileage, it nearly due for a new replacement.
- It's winter, so run 5W30 oil.
- Clean out the PVC and the crank-case breather bell.

Those things mentioned above can be culprits too for your problem. However, the IAC is usually the easiest to clean and tends to be the first thing to stumble the idle. It may need replacing too since your mileage is high.

The mileage is over 90K. It may be a good time to for a new catalytic converter and new O2 sensors now. Avoid the Bosch sensors since they are known not to work properly with our vans.

 

Thanks for the responses.

The cap/rotor, plugs and plug wires where replaced at 100K. I will try a new IAC and replace the PVC valve.

Thanks so much for the advice.