Instantaneous fuel usage, idle is incorrect

[VT97]

have noticed something with the instantaneous fuel usage readout on the display, recently its been showing a reading of 1.0 at idle, instead of the 1.5 which i believe to be the correct value at idle, i have swapped the TPS from a mates car to see if that was the problem and it still shows 1.0, so i guess that rules out a faulty TPS, not really sure what to check next, the wiring diagram in the Haynes manual shows the coolant temp sensor wired in series with the TPS, just wondering if the coolant temp sensor is faulty can it effect the TPS?

also the engine surges every once in a while (2-3 times a week), could the leads or plugs or coils effect the TPS too?

changed the leads about 50000km ago
changed the O2 sensors about 20000km ago
changed plugs about 10000km ago
recently cleaned out the throttle body and IACV
recently cleaned the MAF
coils are original i think

error codes:-
32 - Mass air flow sensor or circuit problem (caused by not reconnecting the sensor)
44 - Lean exhaust
64 - Lean exhaust

when i cleaned out the throttle body i forgot to reconnect the MAF , thats when the engine light came on, reconnected it and reset the computer (disconnected the battery), it hasn't logged any faults since (1 week), so I'm thinking thet MAF isn't faulty, I'm going to get a new coolant temp sensor, and if that doesn't fix the problem then im stuffed as to what it could be.

Hopefully no error codes come up, ever again, I mean EVER. Touch wood!!!

[VT97]

Fixed the problem of the incorrect idle, the rubber o-ring wasn't put back on the IACV after I had cleaned it out causing a vacuum leak I guess, all good now idles at F1.5 l/h...

[nathans1987]

what the correct ls1 idle value?