Truck Repair: Anti-dieseling valve operation, jeep wrangler, air conditioning compressor

Question
My grandson has a 1987 Jeep Wrangler that dies when he is driving and lets off the gas to slow down and downshift. The anti dieseling solenoid barely moves when the ignition is turned on. Less than 1/16 ". It also has a vacuum dashpot on the anti dieseling valve linkage but there is no vacuum going to it. The hose goes up to a vac  block with wires going to it. There is vac on the other side of the block. I assume that it is controlled by some sensor. When you let off the gas is the high vac suppose to push the valve linkage out to prevent dieing? I increased the idle speed screw to around 1500 rpm to try to prevent the engine dieing when you let off the gas when driving. He has to try to work the gas and brake at the same time when coming to a stop to prevent the engine from quitting. Do you think this problem is with the anti dieseling or the idle circuit in the carburetor. I am not sure how that vac is suppose to work with that system. He is also missing a muffler but I don't think the loss of back pressure would cause his problem. Any info you could give me would be appreciated. Thanks.

Answer
Hi Don,
If I remember correctly, the dashpot is more to prevent backfire from the throttle plate closing too quickly, but it shouldn't stay out to set the idle.
The antidiesel solenoid is actually what you set the idle with after the choke opens, and the screw comes off the fast idle step.
But even without the idle solenoid touching, I believe it should continue to idle, but very low, which would be adjusted by a minimum idle screw.
Usually the idle solenoid rod should come out to just touch the lever, but not push it, but when the lever is moved away, it will come out more, and hold the idle faster, till the ignition is shut off. This was also used sometimes in conjunction with the air conditioning compressor, to speed up the idle when the a/c was on.

I'm thinking some Berrymans sprayed in the carb...all the little holes.

Van