Many idle surging problems are caused by the air meter. Ever hear of "fan wash". Open filters in the engine compartment can catch waves of air from the stock fan and disrupt the air meter.
Non laminar flow coming in the filter and inlet bends at low rpms cause variations in meter readings. Moving the meter around may allow you to "catch" the air at a nice smooth air flow point.
Not all inlet tracks can be set up with a smooth straight length of pipe/tube before the meter. Therefore some experimenting is necessary to find the best location. When this doesn't succeed the in inlet air path must be straightened. Then when this is not the cause a voltage reading of the meter output signal should reveal whether the meter is at fault.
I have used both the Pro-M 77 and the C+L 80mm in supercharged and NA, in blow through and suck through modes. I like them both. The C+L is easier to service but the Pro-M comes with a better data sheet.
With any meter you need to be concious of how it is installed and how piping transitions into and out of them. Anyone with a 94-95 can testify how important this is.
Mike
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