99 Silverado shuddering and sporadic shifting. Help!!!!

[flash12]

I have a 99 Silverado 3/4 Ton 4x4 Auto, 6.0L, Extended Cab, Shortbed.

I started to notice while towing an enclosed trailer towards the end of summer, which while towing I pull my automatic tranny down into 3rd, that when going up hills the truck started to cut out and shutter. The truck also while not towing and running in overdrive will cut out and sputter and I seem to get some sporadic shifting and the torque converter kicking in and out. I replaced the fuel filter thinking that it was plugged and was cutting down on my power. That quieted down the fuel pump whine but did not help the shudder and sporadic shifting. Do you think it is an engine problem (plugs, electrical, Etc.), or do you think I have a torque converter or transmission problem? Please Help, I don't know where to start!!

[flash12]

Does anyone have any suggestions of what to look for. Like I said I have changed the filter. Is it possible its plugged again?

[2000CAYukon]

Sounds like your ECCC is having problems. Take a look at this post from my Impala forum: http://www.impalasuperstore.com/nais...TOPIC_ID=25600

//2000CAYukon