Guys I am facing some peculiar problem with my Motor/ESC setup.
Here are the details
Motor: Turnigy NTM 3536 1400kv
ESC: Turnigy Plush 60A
Battery: 4000mah 4S 25C
Prop: 8x4
Anyone using this combination?

When I increase the throttle I can see the current draw slowly increasing as seen on my OSD display, but say after 2-3 seconds, the i could feel reduction in thrust and current drops for around 1sec and again comes back to normal. It is definitely not due to Voltage sag as Battery is able to handle the load.
At full throttle it ranges up to till 39A.
I am regularly seeing this problem during the static test. Now I fear to do the maiden due to this.

If you remember. i had similar problem with my easy star motor Emax 2836. It will be helpful for me also.

Does this happen again after coming back to normal provided throttle is at same position as earlier?? If so, then check you entire connection from winding of motor to battery as there might be some broken threads in wire.

Use a separate BEC or use separate receiver battery.
Your some electronics blocks to work ESc continuously.

I am already using a separate 5A BEC.
Its a new motor out of Box. This doesnt happen if i remove the prop and do the test.
I will test it with a different ESC and see once.

One particular brand of lipo four battery I have seen this. I do not want to name the brand. It is not delivering the claimed C rating initially but after few second when the lipo warms up it starts giving more amps. I believe it has got something to do with ambient cold climate. In fact if used that particular lipo for higher C application and do quick throttle rev up it drops voltage so bad initially ESC cut out happens. When used with watt meter you can infact see voltage rising as lipo gets warmer and wattage delivered increasing.

If this is the case it should have happened near to full throttle or somewhere near three fourth throttle.
I am seeing this problem even when current draw is just 4-5amps which comes to just 1C. I will update the video today.

No this happens in all throttle range. The lipo actually behaves as if it is of a very less C rating initially and as it warms up it starts delivering more voltage and amps. You can choose any throttle range and fix it there, you can see the voltage in watt meter voltage raising up constantly with time for same throttle range, and wattage thrust and prop speed increasing with it.

I have heard lipo also required to be sort of runin like an engine for first few cycles before it delivers the full juice for subsequent usage. It may connected to this aspect.  I don't know how far this statement is true.

I've had this problem with a motor and the reason was found to be a broken strand in one of the wires.