GMC Jimmy COLD DRIVEABILITY ISSUES.

I am experiencing an intermittent cold driveability issue with my 2000 GMC Jimmy 4.3L, automatic, 4x4. Symptoms: on initial cold start engine starts and idles fine. Upon acceleration at approximately 1800-2000 rpm the engine starts to surge right as it is trying to shift. When it does shift the engine runs smoothly until is reaches the same rpm range. I can accelerate through the surge and the vehicle will power right on up. No CEL. Fuel pressure and supply are fine. I have also noticed that the TCC will not engage when this is happening. At highway speeds the engine surges as if a fuel/air issue. Again no TCC. After the initial drive I can turn engine off for 15 minutes and restart with no driveabilty issues. Tried the tap on the MAF sensor. No problem. I disconnected the TPS and the engine ran fine for three days all be it with a CEL. Replaced TPS and ran fine one day. Ambient temp that day was a little higher that day. Next day back to the same old issues. Cap , rotor and plugs have been changed. Any ideas ?

Go to Auto Zone or Advanced Auto and get the codes pulled. This is a free service.
Post any codes found.