help cleaning up data and retrieving the time of day for high and low values...

[yertleturtle]

I have several files (txt) for different trading instruments that are in the following format:

yyyymmdd hhmmss;open;high;low;close;volume

There should be 1 line for every minute of each trading day going back to 2010. Some of these lines are missing. What I would like to first do is fill the gaps. If a minute value is missing I would like to create a line with the closing value of the previous line for all 4 values of the new line but only if it is between the hours of 9:30 and 14:15 and monday-friday (the pit trading session).

The second thing I want to do is pullout the highest high value and the lowest low value of each day and the time that these values occurred but only during the pit session (9:30 to 14:15). I've included two files comprising almost 6 days of data if anyone can help.

Also if I'm being stupid and this is better accomplished in excel please let me know.