When Idling or driving slow it feels like it has a Miss, it has a new Distributor Cap and Rotor, what are the most common things that can Cause this, I will be reinstalling the Cap and Rotor, just encase they installed it wrong(I heard that can cause this, but after the top of third gear and into 4th it's hardly Noticeable, It's made 3 trips of 150mile round trip each time and seems to run great other than that Miss fire or whatever it could be.
Thanks for any help you guys can Provide.

 

Blinking check engine light indicates a misfire is occurring. You can't put the cap or rotor on incorrectly unless you've really gone full retard because they only fit in one orientation. If you put them on in any other way, they wouldn't stay attached, or the vehicle wouldn't run at all. It's certainly possible the cap and rotor are garbage though. A quality cap and rotor set is actually pretty cheap, but junky cap and rotor sets are plentiful and nearly free. Now if the whole distributor unit has been out, that's a different story. If there are 10 ways to put that in, 9 are wrong.

Visit your local Advance Auto or the like and have them check your code. Should be P030_. If the last digit is a 1, 2, 3, or 4, it'll point you to the cylinder of that number. If you find any combination of those, check the involved cylinders. Swap spark plugs with a cylinder that isn't misfiring and see if the misfire moves. Kind of difficult to swap wires since they're all of very unique lengths, but investigate the wire leading to any suspect cylinders for bare spots in the insulation, burn marks, cracks, general damage. If the last digit is a zero, well, good luck. Take a look over everything that's ignition related. Take a look at your fuel injector wiring too for damage. If you get a P0300 AND a unique cylinder code, focus on the identified cylinder. Sometimes the 300 code piggy-backs on another code.

Lack of fuel can also create a misfire, but in this case I think a lack of spark is more likely (and usually easier to diagnose), so start there. If your spark plug wires are old, I'd put my money on that.