LD9 Misfire

[NightCelica]

Hi Everyone I'm new here!
My owns a 97 Grand AM with the LD9 with Auto Trans. The problem is the car gives a code of Po300, I know this a Random/ Multiple Misfire, but I'm not sure why. The engine ideal very rough and you can hear it missing of two cylinder from the muffler, under load it missing and if you rev the engine (no load) it still misfires. This started happen as my Wife was driving home from Chruch Sunday morning. The engine has 142,xxx miles and in the last two half years the Rad, Thmerostat, Heater Core, upper and lower coolant houses have been replaced, by me.
I replace both the Coil pack as one tested bad, the coil
housing, spark plugs (Bosch) and have ordered the spark plug boot. After replacing the coil housing I got the car to run on 3 cylinder instead of two that tells me that it is not a spark problem, second if I add little gas to the intake the ideal smooths right up for a second or two. The car does start a little harder than normal

Thank You

P.S. Today I'm planning on checking Injectors resistance and the TPS.

[NightCelica]

I checked the TPS, and it was with in spec, but how do you remove the Injector connectors?