2005 gmc canyon

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control

I recently had similar symptoms from my Kia Rio, hard to start, bad idle in gear, etc.
Ended up being the idle air control valve, you can try cleaning yours with carb cleaner and see if there's any difference.
A clogged fuel filter can produce the same symptoms too, that might be the easiest thing to start with, then it's just a process of elimination from there.

yes, the filter is on the frame rail on the left side (driver side)at about the back of the drivers seat

not recommeded to clean .....replace ..is the name of the game on these.....hope it helps....by the way have u replaced fuel filter it makes these things idle stupid at times....

Sounds like you may be experiencing one of a few possible issues. If you have an external fuel filter, you may consider in replacing this first. If the filter is part the fuel pump inside the fuel tank, may have to replace the entire unit. Might need to drop the tank from the vehicle if you do not have a was to access from the inside.
Do you have any codes in your ECM ?

How do i remove the cover on the engine to get to the spark plugs & were is the purge throttle valve located?

From http://www.obd-codes.com/trouble_codes/
The P0300 is a misfire and P0506 indicates low RPM at idle.

A misfire can be caused by poor ignition (spark plug, plug wire, coil, ignition module/engine control module).
OR
Poor air/fuel (air filter, fuel injector, fuel pressure, fuel filter, fuel pump, bad gas, or engine control module).

Check your maintenance requirements and see if any of these items are due for replacement first.

You need the idle control solenoid replaced. It is the dealer that will fix it for you.

Good luck.

yes and plugs and wires

there is recall because of this problem. the same thing ws going on with mine. contact your gmc dealership. it is a valve problem in the head.the recalll is not published but if take it to the dealer he can check to see if this the problem. this was a cyl. head problem.