Last time I had this exact problem it was the coolant temp sensor (Temp II). Could be the connector I suppose.

> Date: Sun, 20 Mar 2016 20:58:40 -0500
> From: jason.ellis@ME.COM
> Subject: Vanagon syndrome...it sucks!
> To: vanagon@GERRY.VANAGON.COM
> 
> Ok all, I've searched The Samba and tons of other websites for my issue. Maybe one of the gurus here can help. 
> 
> I have typical vanagon syndrome symptoms. Driving on highway for a while, then suddenly loss of power and bucking.  Turn off engine, restart and all is good for an indeterminate amount of time. I did notice that just before (10 sec or so) the power loss starts, I seem to have a smoother running engine with a hair more power. I also had the syndrome start and I exited the freeway with very little power. I shifted into 3rd and it chugged a couple of times and the BAM, like a switch was turned on, the van power came back. Drove home another 30 min on highway with no problem.
> 
> I have done the following:
> 35v 22uF capacitor between 2(+) & 4(-) on harness to AFM
> New fuel line, pump, filter, tank, and pressure regulator
> Refurbished, cleaned and flow tested injectors 
> New alternator harness
> 
> I have not cracked open AFM. I started to, but I didn't want to screw up anything. 
> 
> Any thoughts?  Anyone have a spare good AFM I could test out?  I hate to spend money on a AFM when I could be sourcing parts for either an engine swap or a Megasquirt setup. I'm at my wits end. I drove about 70 miles on Friday and during a 30mile stretch I had the syndrome pop up every 1/2 mile.
> 
> Thanks for the help!
> 
> Cheers,
> Jason Ellis