plug in NEWmass air ml wont start unplug mass air truck takes 3 4 5 times to start

[junebug]

TAKES 3OR 4 OR 5TIMES TO START TRUCK EVERY MORNING FOR LAST MONTH (99 ML430) ......... TURN THE KEY DONT PRESS GAS AT ALL TAKES 3 OR 4, 5 TO START UP ......RPM GOES UP FOR 5, 6 SECONDS THEN SLOWLY DROPS AND CAR SHUTS OFF AND THEN I START IT AGAIN ......TOOK TO MECH . HE PUT IN NEW MASS AIR STILL DOES IT ........ ........WE BOTH SCRATCHING OUR HEADS ........because if u UNPLUG NEW MASS AIR STARTS FIRST CRANK .... BUT PLUG IN NEW MASS AIR TAKES 3 4 5 TIMES TO START AGAIN ... PS FUEL PRESSURE IS NORMAL PER MECH ...........SO WHATS WRONG HERE ?