Tried to get truck smogged and it failed. Got codes and fixed problem, now the computer won't clear. What can I do?

 

Reset PCM by disconnecting either KAM fuse or battery negative cable for 10 minutes, then reconnect and drive for a week or two before re-testing.

If the original fault codes are still present at that time, all it means is that you didn't fix anything and the original problem is still there.