took it to a LPG installer.

We bypassed the lamdba controlled solendoid with a manual by-pass valve.

Have managed to get a good idle and got it about right at 3000 rpm.

On the road, its still is a bit juddery. Indications are pointing towards ignition system....

The Saab engine management may go into some sort of fault mode if its unable to see the injectors, which may explan why you're encountering ignition issues when you switch to LPG.

With the R90, where does vacuum line from that connect too on an XD Weber carby. Got this set-up but last owner pulled the LPG vacuum line off as they didn't like LPG (wf??). Is the vacuum from above or below the carby butter-fly's ?? All I need is to add the vacuum line and it's a goer on LPG again, so a bit cheaper to run.

Any help grately appreciated