Idle switch question

[eatthebiscuits]

Hey everyone, I'm after a bit of help with my Suzuki escudo. Symptoms are:
I'm only getting 320km from a full tank of gas.
Slight bog on acceleration (hot and cold), but only when first pressing accelerator pedal. Revs and accelerates great right up to 100kph otherwise.
Low rpm at idle, engine shakes a little and seems to misfire at idle.

I have tested and calibrated the tps according to fix kick instructions. Everything checks out right apart from the idle switch goes from 0v at idle to 11.7v off idle. Shouldn't it be 5v? Is this a clue to some of the symptoms I'm experiencing?

I've given it a good tune up. New HV leads, timing belt, spark plugs, dizzy cap, checked and repaired sheared crankshaft keyway, set ignition timing, checked compression (155 all cylinders), checked fuel pressure (36psi).

Any advice would be awesome thanks!
Brendon

Hey thanks! It's a 1992 1.6L 16v Mpi SOHC Sq416, 4 door with the 4 speed auto transmission
Fuel tank has 55L capacity.
Yes it has full power at WOT. Just a hesitation when taking off.
Tacho on dash not working, but just feels low with the shaking/misfire.
Will check country code when I get home tonight.
Yes fuel pressure was 36psi at idle.
Would a vacuum leak cause this hesitation and higher fuel consumption? It does have a 2in suspension lift and 30in tyres.