Matthew

About your engine surging: I had similar problems on my 2.1 Digijet. Like
mine, maybe your system is also feeding excess air past your throttle body
which means one or both of 2 things are faulty: 1) Idling control unit
(behind right tail-light cluster  2) idle valve (sits right on top of
engine).

Try removing your control unit. You may have to adjust your idle screw to
keep the engine going: bring it to just over 1K rpm at hot idle. Now ride
around for a few days and check whether you are still surging. This worked
wonderfully for me, even with air-con!

FYI, the control unit controls the idle valve which allows air past the
throttle body to keep the engine from cutting out under load, ie. air-con,
power steering. A fluctuating idle means that the valve opening is
fluctuating.

Good luck!
Nigel
Cape Town, SA
89/90 caravelle syncro

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