Bobcat 864 turbo

Still struggling with the Bobcat 864. It is not displaying any fault codes, but it simply is unusable in its current state. Runs for a few minutes but quickly cuts out under load and starts belching block smoke as if starved for air. Five years ago the local Bobcat dealership installed a replacement engine.... I think it actually is slightly different than the original As near as I can tell, the original probably was a Deutz BF 4M1011F, as that is what comes up whenever I try to source parts. The replacement engine is a BF4L1011F. Perhaps not a major difference, but when I looked into a replacement turbocharger the TC model numbers for these engines are different. Not sure if this would make a huge difference, but I don't think the loader has ever worked correctly since the replacement engine was installed. There is a ton of air moving out of the blower on the right side of the machine, so I am guessing that the turbo is functioning-- or at least partially. I removed the air filters altogether to see if inward flow was somehow restricted. It actually would stay running then, but still bogs down under load. I noticed that there is a sensor mounted on the back of the air cleaner with wiring code 3700. This apparently is for an "Air Cleaner Switch". Not sure where there actually is a switch or how this functions, but could this be the issue? I have no leaks on the head gasket, and injector lines all seem fine. Not sure about the injectors themselves and/or how to determine if they are at fault. Any insight would be very much appreciated. how this functions