I have an impco LPG setup (dual fuel) on the EF, and I've always had an annoying problem with it, but tollerated it so far.

It has the Impco CDP-Oz controller which uses the EGO sensor for mixture, and it controls the mixture by pulsing a solenoid valve which applies a light vacuum to the balance line of the converter.

My problem is as follows: If I floor it suddenly I get a moment of silence as the engine almost dies, but then recovers about half a second later. If I set the converter up with the balance line vented to the airbox (no computer control), it won't do this.

I am assuming now that this is because at WOT, all vacuum disappears and the computer can't control it anymore for a brief moment. Hence the engine seems to die.

What I was thinking of doing was to make a vacuum reservoir, and a regulator to supply a "lighter" vacuum to the solenoid, but I was wondering if there is an aftermarket kit that can be bought instead (if this is a common problem). I searched a bit, and found that extra vacuum reservoirs are commonly installed on smaller engines when getting vacuum actuated cruise control fitted.

Does such a "fix" already exist, where can I buy it, or is there another work around, as I can't get anywhere near 400k's a tank without the computer