Went out tonight to start the truck after about 2 days of not running, it idled rough at start but when i went to drive away it barley ran and had noooo power, seems to be only running on a couple cylinders, check engine light is flashing, just changed coil pack plugs and wires last month. any ideas

 

Get the code form the CEL

 

retrieve the codes for sure. Although you replaced the coil pack, its possible the new one has crapped out. Make sure the connector is plugged in and check your wires to be sure none of them came loose.