Hi, first off what firmware are you using?
Secondly, what is actually happening when te PW starts dropping up and down? Is it because the engine is running roughly? If you are holding your injectors open for longer with the effective ramp-up time at 3ms it might be because the fuel map is too low at idle - so you are overcoming this by forcing the injectors open for longer with the ramp-up time.
What I would do is:
Check the req_fuel value. Save my current maps.
Halve the req_fuel value, and set all of the values in the maps that are around idle and low load (so a 4x4 or 6x6 part of the table) to 100 on the VE table, and what ever the correct sort of idle advance is for your engine (something around 15-20degrees), ensure that your lambda table is also set to 1.00 in the 4x4 or 6x6 part of the table.
Set the effective rampup to 1000
Now start the car and start to map VE at idle - if you change the values in all the 4x4 or 6x6 cells at the same time you should have an easier time as the engine is less likely to run off an lean out or get too rich as the RPM & vacuum rises and falls.
Once you are happy with the idle make a note of the VE and PW values and compare this with your original fuel map (remember to half the VE number when comparing it with the original value).
Why do you half the req_fuel value? Well thats because it gives twice the resolution of adjustment, which can really help with getting idle fuelling spot on.
Rob