Import taking over 24 hours

We have been working on an import situation for a couple of months now, and 
I would like to get some feedback from some of you on this.  We have a 
RS/6000 which is running some older cobol programs, we are not in a position 
to replace those programs at this time, what we need to do is import that 
data (from standard unix cobol files ACUCOBOL to be exact) into several 
physcial files on our 9406-170.  

We are using MS Access (which I hate but it serves its purpose here) to dump 
the data from the cobol files into tab delimited files which are then ftp'd 
over to the 400 and then imported into the physical files.

Everything does work but it is taking around 28 hours for the import process 
to complete.

The files can be broken into three groups, customer master data - which 
takes about 20 minutes to complete....the flat file is approximately 8.5mb 
in size.  We have several line item files which are imported into one single 
physical file, the flat files for this group are approximately 400mb.  The 
third and final file is a header file which is approx 150mb in size.

We had an outside vendor actually write the code for us which as I said 
before does work, but it is taking a very long time to process.   

If anyone has any ideas or thoughts on how we can speed this process up I 
would love to hear those ideas.  I need to check with the legal department 
before posting the code since I am not sure what contractual obligations we 
are under as far as the code goes.

I do know that he is splitting the fields up by checking for the tab and 
then writing the data to the file. the header file has quite a few fields in 
it, and if anyone wants to know the number of fields I can verify that and 
re-post.