Setting distributor and setting TDC Wrong?
 

I just did my intake gasket on my 99 blazer 4.3. We didn't mark the distributor correctly and I had to set the timing back to top dead center for the distributor. I just want to know is can you set it a little off, enough for it to still start? Because I got it to start and it just seems like sounds a little rough and it sounds funny. Almost like there is no oil in the engine. (But there is). Could the timing maybe a little off? Would it start if it was? Also I have a crank sensor error for my "check engine" light. Could that cause the rough sound?

Run through the steps listed in the link below:
EDI Engine Timing

I did find these exact directions. I did exactly the way it said and these were the only ones that got my truck started. I will do it again just to be sure, but how do I set the cmp retard, what scanner do use? Or is this something that a shop needs to do on a computer? Do mean to ask dumb questions, but this was the first time I did anything like this, I've only been working on my truck for a few years. Never anything to invole like this..