Serial data decoding

Please help!
I have a string of data as the result of serial to parallel hardware
conversion.
I need to decode this string into correct bytes.
The start of a byte position is unknown.
In this particular case, part of my data is as follows.
Serial data string: (not rs232, straight serial data)
01001010010010010101001001001001010100100010010001001010
This was read through a ****ft register to get 8-bit bytes to store in
memory
as:
4A 49 52 49 52 24 4A
I need to decode bit pairs into corrected bits.
00 = 0  01=1  10=0  11=Illegal
So that means every 16bits  =  8bit byte
Ultimately I need to find certain values within this string which confirm
bit decode positions.
Somewhere within this string of bits there is a pattern of 4E 4E A1 and on
paper I do see it.
The actual data memory size to decode is 16k.
Thanks,
Ed