Service engine soon light is blinking and when go to accelerate its feels like it don't want to go and is slugish not really alot of power. Could it possibly be the spark plugs? the wires looked ok.

 

You need to get the codes read. Most of the chain part stores do it for free.

 

If the light is on, it means the TCCM has stored codes. Definitely get them read. Problem will likely be that the code scanners used at Autozone/Advance Auto/etc will not be able to access the TCCM for codes. It will need to be a higher feature scan tool for this type of access.

 

Just to be clear here is it the 4WD or Service Engine Soon light blinking? Your post title said 4WD. "If a misfire condition exists that could potentially damage the catalytic converter, the diagnostic executive will command the MIL to flash at a rate of once per second during the times that a catalyst damaging misfire is present". (from the GM Service manual)
A good scanner/reader can see the misfire history in the computer so you can narrow it down to specific cylinders, but if you don't know the history of the truck (last time it had a full tune up) plugs, wires, cap & rotor is an excellent place to start. Appearances of the wires doesn't mean much. A better back yard test would be to start the truck in the dark and spray the wires with a spray bottle of water and watch for a sparky light show.

 

Ha. Yeah... I read the description and missed the first two words of the post.

Plenty of posts on the flashing CEL.

 

Why wait until dark? Just grab one wire at a time. You'll know if they are leaking. Only bites for a second.