You might have the cooling system pressure tested. I'm glad to hear you already tackle the intake gasket, cause I caught mine a little too late and had to rebuilt my motor lol.
No problem man...Just trying to help you do this all in one setting, and if you want to you can replace the water pump since that has to come off also.
This is what I used when I rebuilt my motor in my 96 http://www.oreillyauto.com/site/c/detail/CLO0/C3017.oap?year=1996&make=GMC&model=C1500&vi=1144202&ck=Search_C0422_1144202_162&pt=C0422&ppt=C0141
I had the same problem with my first NV3500 (mated with a 350) except my locked it self in 3rd and grenaded the bellhousing , and shot out the driveshaft...Then the NV3500 in my V6 ECSB lost every gear but 4th...But what I'm trying to get at is from my previous experiences it might be time for a...
Yeah that look pretty much alike aside from the connector...Go ahead and change the fuel fillter before you try a new a CTS and see if that changes anything, but if not change the CTS...Are you losing coolant?...Oh yeah I forgot about the pick-up coil, check that out as well.
Here you go...http://www.autozone.com/autozone/parts/Duralast-Coolant-Temperature-Sensor/1992-GMC-K1500-1-2ton-P-U-4WD/_/N-iwrpvZ9gslt?counter=1&itemIdentifier=146258_0_0_