Need Help!- Controlling the L297+L298HN with PIC

[CyberArtem]

Hello again
With no luck solving the 'crazy' motor problem i am beginning all over again. But this time i want to be sure that i am not making the same mistakes.
I am controlling the L297+L298HN with a pic16f84a that gets its commands from another pic16f877a, i already checked the commands delivered fine and the 16f84a is acting as it should. Now i need some help considering controlling the L297. Here how i control it now : (i am using MikroC)

case "Some Command": // the pic16f84a gets a command from pic16f877a
{
// Setting the direction...
PORTB.F1=1; // Direction PIN, High=CW Low=CCW
// Enabling the motor...
PORTB.F2=1; // Enable PIN, High=ENABLE Low=DISABLE
//
for(i=0;i<200;i++) // Making 200 steps to complete one rotation
{
// Sending a step pulse to L297
PORTB.F0=0; // CLK PIN goes low (The pin is set high by default)
Delay_us(500);
PORTB.F0=1; // CLK PIN goes high again
Delay_us(500);
//
}
//
// Disabling the motor...
PORTB.F2=0; // Enable PIN, High=ENABLE Low=DISABLE
//
break;
}

That's how i control the L297 , is it a good way to do it ?
I must use the PIC+L297 because i use custom software.

-- Old Problem --
I had a problem with this approach that my motor sometimes 'looses' or changes direction even if the same command is given
and misses steps and gets 'crazy' rotating not as i control it. Sometimes all work fine for 5-10 commands and then again undesirable movements and jumps on each new command. Again the command is transmitted ok because the L297 gets a move direction and enable command. I think that's an electronics problem it looks like some capacitor charges up and messes the whole thing. (i have 470uF on 12v and 10uF on 5v also 100nF on each).

I use SANYO DENKI 103H5208-0241 unipolar motor , which i am using as a bipolar (using only 1 coil from each wind)
The L297 pins are not pulled not to GND nor to VCC.

The voltage supplied to the L298HN is 12v with a 7.2 ohm single coil resistance the max amp is about 1.6 amp so the L298 should drive it with no problem.
The Vref voltage of L297 is 800mv (1.6A for the motor)

1) What Duty cycle should i use ? (50%/50% ?)
2) What delay should i use ?
3) When should i enable the motor before/after i set the Direction pin ?
4) What to do the PIN 11 on L297 set it high/low ?
5) Do i need to reset the L297 after each command ?
6) Are the problems i mentioned has something to do with the fact i am using a unipolar motor as bipolar ?
7) Can be the L297 internal OSC R/C values wrong ? (using : R=22k C=33nf)

Thank you