Thank you SO much to everyone for sharing their knowledge! It’s kind of overwhelming to sort through it all to figure out how it might apply to our situation! Your information points to our lack of experience – your efforts to get us pointed it the right direction through a process of elimination is appreciated! The sluggish idea came, in part, from people’s comments with the same RV/engine – sounds like it’s not totally out of line with other’s experiences here. When we first started driving ours – we were powering up a mountain – as you say with the engine screaming – the engine shut down – and we had to be towed to a dealer. The computer showed injector codes – which could not be replicated at the dealer. Only definitive thing that thing that showed up was a blown fuse. This hasn’t happened again – yet I guess we hesitate to push the engine until it screams because of past experience. Oh – did I mention we hadn’t purchased roadside when the engine quit? Talk about live and learn! Re: the flatlander reference - please remember we're used to a well oiled machine ;) We did read and think about the tuning programs - but didn't know if it was something we should pursue or if there is another problem. Fuel filter has not been changed - so I think that's something we will have done.