slow picking up revs

[Trip]

When pressing the throttle on neutral, the revs go down to around 600rpm and then go up.

Everything is standard for now (apart from a rebuilt engine)

The only trouble i had, it was idling at 650 rpm so i re-calibrated the TPS to read correct voltage (0.44v idle and 4.23v at WOT) and had to adjust idle screw to get idle to 950rpm.

What i checked are the following:
Fault code and got a clean 55 code
Fuel pressure remains at 3bar
Idle vacuum is -9psi (reading from after the Throttle bodies)
Idle AFR hoovers in the 14.7 range
MAF connecection and ground
Oil pressure when warm is at 40psi (2.7bar)



Any ideas what i should check and/or replace ?

 

[Fusion Ed]

How are you getting this data? If its datascan show me the datalog. If you cant I reckon it can only be your ignition base timing.

 

[Trip]

How are you getting this data? If its datascan show me the datalog. If you cant I reckon it can only be your ignition base timing.

What i checked are the following:
Fault code and got a clean 55 code: By shorting the pins of the consult port
Fuel pressure remains at 3bar: got a gauge attached to the FPR
Idle vacuum is -9psi (reading from after the Throttle bodies): gauge
Idle AFR hoovers in the 14.7 range: PLX datalogger
MAF connecection and ground: checked it myself with a multimeter
Oil pressure when warm is at 40psi (2.7bar) Gauge