16F877A timer to capture in microseconds

[sycluap]

I modified the Olympic Timer program, by replacing the:
TMR1RunOn.HighByte= $FC
TMR1RunOn.LowByte=$18

and deleted the TMR1RunOn=TMR1Preset+TMR1RunOn, to directly load the TIMER1 preset value into the timer1 register.

This make the timer by the program runs faster than used to. Until I change the value to $FF,$FE, the timer can have the timing interval very close to 1ms, but still slightly delayed, as I compare the timing (seconds) with a watch. The watch is about 2x faster than the timing by the timer.

Attached is the code I wrote by referring to the Olympic Timer by Melanie. Is there any problem with the code? Any solution for that? Thanks in advance.