Some more info would be good.
1. How many miles?
2. How are you reading code?
3. How did the Coil look when you changed plugs( very common problem)
From what you said i can assume the next place I would go is the coil.
Most likely this problem is your coil. If you are unable to change this yourself, you should take it to a mechanic as soon as you can.
I'm not a mechanic / technician but I BELIEVE if the fuel injector is restricted so that the proper air - fuel mixture is not getting to an engine cylinder , that an engine cylinder misfire can occur ( that is only one of the causes of an engine cylinder misfire )
It means that more than one cylinder has a misfire history. PO301 would be cylinder number 1 misfire. PO302 would be number 3 cylinder misfire.
Try replacing the plugs and wires
Misfire on more than one cylinder. Start by replacing your plugs and plug wires. If that does not solve the problem, run a compression test to determine if you have a burnt valve.
That would be that there isn't enough gas getting to them
po300-Random/multiple cylinder misfire detected. po303-Cylinder no. 3 misfire detected. po306-cylinder no. 6 misfire detected po300-Random/multiple cylinder misfire detected. po303-Cylinder no. 3 misfire detected. po306-cylinder no. 6 misfire detected
Usually a misfire.
Cylinder #4 misfireCylinder #4 misfire
Cylinder #2 misfire.Cylinder #2 misfire.
try checking your 02 sensors
Stop by http://www.coloradofans.com there are different people that have had that problem. you can probably message them personally and see how they got to that problem. P0300= Random/ multiple cylinder misfire detected P0301= Misfire detected- cylinder #1 P0302= Misfire detected- cylinder #2 P0303= Misfire detected- cylinder #3 P0304= Misfire detected- cylinder #4 p0305= Misfire detected- cylinder #5 P.S. These are Diagnostic trouble codes, not vechicle id numbers.