2006 F350
209,000+ miles
Bullet Proofed @ 110,000 miles
No tunes at present time - stock air cleaner

Been a long time since I have been on here because the 1st 06 was replaced with the current run which ran fine up until now.

Had the oil and fuel filters changed in Denver. When I headed west over the mountains into Breckenridge I noticed the truck "stuttered" and was putting out black smoke at between 2200 - 2500 RPMS. When I mashed the metal and brought the RPMs up over 2500 RPMs the truck would smooth out and accelerate fine. I was thinking maybe it was the altitude that was causing the problems but it has continued even when I got to lower elevation all the way to the east coast.
If I accelerate gradually through that RPM range the truck runs smooth - problem is only when the engine is under a load. IMHO acts like it is not getting enough air on heavy acceleration.
Checked MAP hoses and intercooler tubes and they appear to be okay - no leaks found.
Looking for suggestions
Thanks in advance for replies

 

I'm sure you checked the "new" air filter too? A good shop in Dallas once left a red shop rag in mine...we had a good laugh about it..but about those RPMs under load there is alot of vacuum in the air intake. Just my $0.02

 

Get ForScan Lite for a smartphone
Get the appropriate OBDII adapter to plug it in
Read codes.
Retrieve the EBP, Baro, and MAP values at Key-On_Engine_off conditions and post the numbers.

It could be a number of things.