2002 Mazda Premacy unsteady rev needle???

The car injection nozzles has been taken out to be examined,and they were fine so put back, the car usually starts perfectly without problems, but since the nozzle checks, the car shook unsteadily at idle with unsteady rev needle. The car has been thoroughly checked for hose connections and leaks, MAF passage leaks, and electrical plug cables, everything seems okay. At start however, is unusual, as the rev needle always jumps up to 1.5-2000 rev/min then shakes unsteadily drops to 8-900 rev/min and stays there, unsteadily, and the engine shakes. At idle when the needle drops lower as if to stall, the engine shook harder, and the confusingly the needle jumps back up to 1.5-2000 rev/min again and then drops lower again to 8-900 rev/min, and this carries on and on until it is in motion that's when everything seems fine as the needle is steady and the acceleration is just fine. At stationary with gears D or R on (brakes depressed), the car shook harder and sometimes stalls, except when the gear is switched to N at idle, the needle unsteadily shakes between 8-900 rev/min.

Could someone please help on this?
all the best!
Thanks