This site has saved me hundreds if not thousands in "shop" dollars. Thanks to everybody who is involved!

2010: Blazer starts jerking. Fuel lines leaking in the intake. Replaced the spider and then regular tune up stuff. Has ran great for the past three years.

2013: The hesitation started about a month and a half ago and now it will barely accelerate and it feels like its about to shake itself apart. Hot or cold.

DTC's

P0122 - TPS Low voltage
P0135 - HO2S Heater Circuit Bank 1 Sensor 1
P0141 - (GMT360/370) - HO2S Heater Circuit Bank 1 Sensor 2
P0340 - Camshaft Position Sensor A Circuit (Bank 1 or single sensor)
P0441 - ???
P01406 - EGR Valve Pintle Position Circuit

I went ahead and replaced the TPS, Cam Sensor, and 02 Sensors but nothing has changed. I did change the plugs when this started. The EGR code has been there for a while. I have cleaned the EGR multiple times. I have had the plenum off twice and everything looks fine. No fuel leaks. I did do a fuel pressure test and everything was within range. I did change the fuel filter also. I haven't had the chance to get the codes read again and see if anything changed so I'm still trying to work through the problem. Haven't tested sensors either. Wiring looks up to par. After hours of research on this site, I am really starting to think the cat.con. might be clogged. Haven't done the nighttime check to see if its glowing or not but it is super hot under there.
Here's where it gets a little weird, for me at least. I drove it today about ten miles. I started smelling burning plastic then noticed it was me when I came to stop and it was smoking from underneath. When I looked under the truck I see this melted black plastic like stuff coming out the holes in the cross member above the muffler. The one hole was dripping directly on the muffler and the other hole was dripping on the driveshaft and spinning onto the muffler and smoking. I have no idea what is going on there.This has never happened. Any help is greatly appreciated.

 

I would say start out by jacking up the back of the vehicle and try to figure out where that melting plastic was coming from. Double check all fuses. The P0441 is usually an EVAP code which relates to canister or vacuum type hoses or leak.

From the type of codes you have, sounds like some type of misfiring issue going on... so with misfires it can be either fuel or ignition. It very well could be a failing spider again.... can either pull off intake to check for leaks, sometimes if you have someone turn key to on position while you stand in front of engine, you can literally hear the trickle of the gas within motor if leaking.
Good luck and post updates ;-)