I have been completely clueless for almost 6 months by now about my 89
Vanagon. I have never had a problem with it and rebuilt the engine about 3k
ago. It ran beautifully until one day it just stopped running right.

It idles and accelerates fine when cold. Just as it gets warm it starts to
hesitate,coughing and backfiring through the air intake when you press on the
gas like if you would accelerate from a red light. It sounds like it is fuel
starved or mixture not kicking in. It just won't smoothly accelerate and rev
up. It seems to have no power and compression is obviously good since it runs
fine when cold.

You obviously cannot drive the van this way. It will hesitate like crazy,
sometimes it will backfire through the air intake other times it will rev up
a little. If you try to accelerate it slowly while in neutral it will go ok
and start stuttering at about 4,000 rpms....

I have had this in the shop and it was sent home without them being able to
diagnose what the problem is...

We have checked everything and still cannot find the problem. The brain and
air intake sensor have been swapped with a great running van. Brain checked
normal with all the tests as well. CO has been measured and hooked up as well
and tested fine, too. Fuel pressure is fine, injectors firing well, gas is
new and i have even swapped the pump as well... exhaust is clear and not
clogged, throttle switch works fine...

Here are all the brand new parts that have been installed since it started
doing this.

4 new injectors, new distibutor, new coil, new temp sensor, new oxygen
sensor, new fuel pump relay and it still does this.

Does anyone have an idea what this problem is??? I am absolutely clueless!

Thanks!