Started happening recently, after a friend drove it and really got on the gas. (~7k rpms, I usually tried to keep it under 5k.) The car has a new starter, the battery holds charge well and new wires were ran when relocated to the trunk. New distributor and set the timing correctly. Fuel filter was changed and the oil was changed to synthetic. ~155k on the engine. When the car starts, it runs great. But it doesn't want to start very well lately. It will try until the battery runs out of juice, and then I have to hook up the battery charger and it finally picks up. Going to change the spark plugs and see if that helps, but any insight would be great.
Thanks in advance.

 

Do a full tune up.