'01 silver engine surging

I have a '01 silverado 2500hd 6.0 V8 with 110,000 miles on it. Symtoms are when I floor it I get some weird engine surging like it wants to go faster, its kinda like a pulse, and I have noticed some power lose in normal running conditions like taking off from a start and excelirating. My check engine light also comes on when I floor it for about 30 seconds. I had my mechanic check the code on it and he said that there was a misfire in 3 of the cylinders other than that it didn't tell him much. So he told me to start with replacing the plugs which I did but it didn't help. I did have my fuel pump replaced 2 weeks ago but I don't see how that could be a bad part. I was thinking maybe an O2 sensor or EGR valve, If anyone has any ideas please let me know. Thanks

Bad spark coils?

I am not sure if its bad spark coils. How would I find that out and how much is that going to cost to fix?

With having 110,000 miles on it i would start with the basics , change the spark plugs AND wires, clean the injectors , replace the fuel filter , clean the throttle body. With the loss in power it could be faulty plugs, wires or a clogging fuel filter. You said when you floor it , it seems like it surges like it wants to go faster, that could be a fuel starvation problem.

In the last 2 weeks I have had the fuel pump, fuel filter and the plugs replaced.

ok , so you have done 2 of the five that i have listed and one that i did not, I suggest cleaning the injectors next and for the cost i would have the TB done at the same time.

I have also ran lots of seafome through it and cleaned the TB, sorry I didn't mention that in my last reply, and I didn't replace the plug wires because they had been replaced in september 2004 when I bought the truck, and also the suging is so predictable I could probably tell you how long it is between each pulse if I wanted but I can't drive and operate a stop watch at the same time. Do you think it could be an O2 sensor or a cloged cat. converter?