Nissan Repair: 2000 Maxima Cutting Out, compression check, miss fire

Question
I have a 2000 Maxima with about 150K.  When it is first started it runs extremely rough, sputters, and miss fires.  After about 1/2 a mile it runs much better, but not great.  There are still flat spots in the acceleration and hesitations. I know there is one lifter that is making some noise (more noticeable in the morning with little oil in the top end).  Would it be possible that the lifter/valve is the cause of bad performance?  I have put new plugs in it, but have not messed with the coil packs or any of the sensors.  

Answer
The flat spots could be from a faulty TPS ((throttle positioning solenoid))).
The lifter could definitely cause the car to sputter, idle rough and miss fire.
Do a compression check of the cylinders, its actually kind of fun on some cars. Compare the readings and get back to me.
Check the timing while your at it, too many miles without timing chain/belt replaced can cause the same problems.