Think Truck is missing

Ok...so i know the people on here can help. I have a 98' chevy 1/2 ton truck, 196,000 miles. When the truck idles it pulses like it is having trouble idling. When I go to get on it on the freeway its like it has trouble accelerating slowly, but if you "get on it" it seems ok, until resuming a normal speed. When I come to stoplights it's like a shuttering feeling, almost like it is missing. Have not checked timing, and have changed fuel filter, wires, plugs, about a few months ago (routine maintenance). Someone told me to try turning off A/C to see if it would stop, but still pulses. Any suggestions.

I had a similar problem a while back, and replaced everything you had replaced. I would try taking a look at the plugs, wires, dist. cap, and rotor, and make sure all looks good. Make sure cap isn't cracked, and make sure roter doesn't have burn markes or look really nasty. My next guess would be a fuel pump. Mine went bad in my 1990 GMC Sierra 3/4 ton and it ran like total crap. I would try checking the above and maybe even purchasing another fuel filter before tearing into something major. It's all about the process of elimination. Good luck!

Check your EGR valve for leaks or to make sure it is working. I was having a similar problem with mine after replacing it and noticed the vacuum tube had come off

What engine and fuel system does it have?
You need to take a good look at your fuel pressure. Get a fuel pressure gauge on it and check the fuel pressure running down the road and make sure it is up to specs.
Any check engine lights? Get it put on a engine capable scanner and look it over. Check for any missfires and look senser data over good. Check for codes past and present.
Post back what you find.
MT-2500

The Vortec engines have a common problem where the fuel pressure regualtor will start leaking (internally) and running poorly and even start setting O2 sensor codes & starting problems. Check your coil ensure you don't have any white marks on the sides, this is a sign the coil is shorting to ground and not getting to the plugs. Slightly increase your spark plug gap by .05 and use the Delco Plat. plug it needs! Is your SES lite on? If it is get it scanned O2 sensors maybe getting lazy.