It is possible either did not get all the dirty areas in front, and rear of set cleaned out or even that the ballast for the unit is this problem since it powers the lamp---lamp will come on and then turn off for a number of reasons.
The set does have a self diagnostic feature which usually is:Mitsubishi TV
Here's something that might also be useful. After you turn on the set, and getthe regular red blinky lights, hold down the Device and Menu buttons togetherfor about 5 seconds.
The Power light will start to flash
in a two digit sequence.
For example, 3 flashes, then 7 flashes = 37.
Here are the error codes, and the corresponding problem:
12 = No error detected, check power supply.
32 = Lamp Cover is open.
33 = Air filter
cover is open.
34 = Lamp abnormality
36 = Light Engine (DMD or Lamp Fan stopped)
37 = Exhaust or Lamp Ballast Fan stopped
38 = Lamp Temperature High
39 = DMD Temperature High
41 = Short is detected
44 = DVI cable
between FMT and Engine disconnected