toyota tacoma p0303 code

i have a toyota tacoma 2001 model, 2wd, 2.4 ltr...engine light come on with a tdc p0303 it means 3rd cylinder misfire. it's distributerless, the four coil packs have all the same resistance 13.5 ohms, i already replace the spark plugs and it run smooth for one day and it become shaky again afterwards engine light comes on again. i remove injector assy. and put 3rd injector to 1st injector vise versa then i erase tdc with my scanner. what transpired really puzzled me light comes on again and the tdc now is p0302 2nd cylinder misfire. any ideas what cause this trouble surface? the mileage by the way is 96000 miles.

Are you sure you didn't install injector three into number two instead of what you thought was one? numbering should be 1 2 3 4 from front to back.
Also you mentioned the miss was intermittent? If so, you can't always tell a bad coil by a resistance test. The reason is that temperature and other factors can cause an open that isn't readily discernible by a resistance test.