Many questions

[TruckerRalph]

Howdy Rawze and Folks! New owner op. Bought a 2010 Pete 386/Cummins ISX CM871 425ST back on Dec 5th. Only had the truck out for the past 2 months. Everything has been going great. Until recently. Now, when i started, i turn the key and let all the gauges cycle through like normal. Thats always non-negotiable with me. After it cranks, it runs perfectly smooth for about a minute then begins to "lope". Like its a big cam hot rod. Not sure if thats normal on a cummins, but i thought i'd mention it. Anyway. Recently i was just driving along with the cruise on and it sounded like something gave out and caused an exhaust leak. When and only when i give it any throttle it will sound like a really old worn out, heavily loaded log truck. Or and old car with open headers. I got to a stopping point and left it running and checked everything over. I'm pretty mechanically inclined and i couldnt find anything out of the ordinary. After a week of this, still nothing out of the ordinary. No visible exhaust soot marks and i cant feel any exhaust escaping. I just recently replaced my Imap and DeltaP sensors after watching Rawze's videos on youtube. The Imap was completely sealed up with soot and the DeltaP was disgusting as well, BUT it looked like it had some condesation in the holes. The EGR cooler "looks" brand new, because its shiny as a new nickle and there are stickers all over it. I hope i really dont have anything bad going on. Thank you in advance.