battery still being drained

You need to do a proper parasitic battery draw test. This will determine if and what the draw on the battery is. Guessing is not a viable solution as you are never sure of your results. You require a digital volt meter that has atleast a 10 amp rating and a battery shunt tool. Install the shunt inline on the negative battery cable and install your meter leads on either side of the shunt. Set your meter for DC current and remember to move the leads into the DC current ports on your meter. Turn everthing in the truck off and close all doors. Open the shunt and record the meter's amperage draw. It may take up to 30 minutes for everything to power down. If you have the Onstar system, it may wake up every 15 mins. or so. Your truck shouldn't draw more than 40 ma at rest. If you have aftermarket equipment like an alarm or remote starter the draw may be a bit higher. The acceptable limit is usually a max of 50 ma. If the draw is higher, you must start disconnecting things one at a time by pulling fuses out, to identify what the problem circuit is. If you really want to rule out the ignition switch, you can unscrew the large connector at the bottom of the steering column. This will disconnect it as well as the turm signal switch.sparky

A shunt is a device or switch that allows you to open or close the connection for the battery cable. When closed, it can allow enough current through it to start the vehicle. You may be able to get one from an auto parts store. Some have a rotary dial you turn to open/close the connection. It will have terminals on either end to allow you to attach your existing negative battery lead to and it to the battery. There are two basic types, one for side post batteries and one for top post batteries. To fix the door problem, use a screw driver to close the latch on the end of the door. This will simulate the door closing against the striker in the body and turn off the interior lights.sparky