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In this paper, we report the synthesis, magnetotransport features, and magnetization of polycrystalline La2/3Ca1/3MnO3:Agx/Inx composites with x = 0, 0.1, 0.2, 0.3 and 0.4. In the case of La2/3Ca1/3MnO3:Agx, the temperature coefficient of resistance (TCR) near ferromagnetic (FM) transition enhances significantly with the addition of Ag. The FM transition temperature (TFM) is also increased slightly with Ag doping. Magnetotransport measurements revealed that magnetoresistance (MR) is found to be maximum near TFM. Very sharp TCR is seen near TFM with the highest value of up to 15 % for an Ag (0.4) sample, which is an order of magnitude higher than for pristine sample and is the best value yet reported for any polycrystalline LCMO compound. Increased TCR, TFM, and significant above room temperature MR of La2/3Ca1/3MnO3:Agx composites is explained on the basis of improved grains size. Interestingly the La2/3Ca1/3MnO3:Inx composites behaved exactly in the opposite way, resulting in decreased TFM, and TCR compared to the pristine LCMO compound. In fact, the grains morphology of LCMO:Inx composites is seen to be inferior to pristine LCMO which is opposite of the LCMO:Agx case. [ABSTRACT FROM AUTHOR]