What is the symptom when a vacuum line collapses or leaks?

The reason I ask is that on our way back from holidays, 5 hours from home
our 86 Westy misfired 2 times in a row and from there on the fuel
consumption went up and noticed quite a bit of loss in power. Hills caused a
major speed loss and from stop signs a took a while to reach 90 km/h. It
almost felt the engine was choking on to much fuel. I was able to limp home.
The Westy never misfired after the initial misfire.

Another Westy owner has a very similar problem and changed the fuel pressure
regulator and AFM. The Westy run for a while but now he is stuck again on
his trip. His Westy runs for a 10 kilometers or so and then dies. Sounds
something heated up and caused the Westy to stop working.

The common thing we both did was install an aftermarket cruise control
(different brand names). I put a T at the fuel pressure regulator for the
required vacuum line and put a new vacuum line in; same diameter.

I ordered a new fuel pressure regulator but after checking the archive I
think it has more to do with vacuum lines getting warm possibly collapsing
or leaking at connections.

Feedback is greatly appreciated.

Cheers,

Hans Brouwer

Cumberland, Ontario
69 Bus (Speedy)
86 Westfalia (Slowpoke)
92 Cabriolet (for sale)

BusFusion a VW Camper camping event in Almonte, 2004
Member: Vanagon List, IWCCC & Capital City VW Club