To confirm the ECT sensor is above the T-stat housing and not the one in the upper intake. If you did replace the correct one make certain the battery to engine ground is solid with no corrosion at the battery terminal or the engine stud.
Pull the spout and make sure there isn't a bent pin. It just prevents the PCM from advancing the timing when pulled (open circuit in the TFI)
I was referring to the dash gauge sending unit in the upper intake driver's side behind and below the distributor. Some are confused between the two.