I have a 1996 F350 Turbo , in 1st gear it is sluggiush after it changes gears it picks its power back up and runs great , it does it every time and only in 1st gear , what could the problem be? It has been hooked up to 2 different machines and trows no codes , I have changed the whole exhaust,and serviced it completely, I am out of ideas , can you help me find the problem?

. Check the turbo--it may be developing problems. If you don't use full synthetic heavy duty diesel oil, it's only a matter of time until the turbo fails. Torque requirements are greatest in 1st gear.

. Check/replace the Variable Speed Sensor (VSS).

. Drop and clean the transmission pan and magnet, change the filter, and refill with synthetic ATF. With PCMs, engine and transmission problems are often inter-related.