Runs rough under load

[mmsalt]

Took the 1999 Alegro Bay out for a ride today, still shaking it down fixing all the little bugs. I had previously had AutoZone do a scan and had a misfire code on the #4 cylinder. i swapped coil packs changed air and fuel filter and scaned it myself using a friends scanner. It came up clean with no codes so off we went. While going up a steep bridge it sounded like it was missing, once we got to the top and were level it ran fine for the rest of the day. It seems like only under a heavy load it happens. I scaned the computer again and no codes showed up. What should I check next.

Thanks
Mike

[cannon man]

plugs n wires

[dsbike]

Is coil pack getting a good ground on the block? Did you clean the mount area before installig new coil packs?

[mmsalt]

Yes the plugs are connected but I didn't clean the grounds. I will do that. It only misses when under a load.