bad coil or ECU ?

AND does anyone have a link to replacing the pick up coil and Reluctor ? sorry for all the "newbie" questions but I am learning lol. and is this an easy swap and "gap" while the Dizzy is still in the motor or should I just pull it and check everything? .. this is kind of the last thing I could think of .. getting gas for sure and runs good untill motor is hot and has a load on it ..