Ok don't immediatly go out and pay someone for a job like this but deffinetly check, from what you say and whay you just purchased I'm going to throw out all those possibilities and say its deffinetly not water in the engine, or spark of any sort but im certain your timing belt is just about done for, your probably missing a tooth or if your unlucky like me your probably missing anywhere from an inch to five inches in a row of teeth on your belt. check your belt for tightness also start your car and listen to the belt even if you have the covers on trust me you will hear a ticking or slapping noise. When your belt starts wearing out trust me you will lose power and it will send your check engine light into confusion but don't wait too long to atleast find out if im right or not cuz once that belt breaks or gets to that 5 inch gap of missing teeth trust me you will be replacing your head!!!
Goodluck to whatever it is but from experience trust me I got some wierd shit that has happened to me in my lude im almost certain thats the cause.

later, luders