OE812

I have a 2001 Silverado 5.3L automatic with approximately 225,000 miles. I recently noticed a large drop in mpg from 17 mpg in mixed driving to 12 mpg. It does not have any engine codes or engine light lit. I ran live data on the OBDII scanner and have the following. Are these numbers considered normal operating figures?

Air ECT STFTB1 LTFTB1 RPM IAT B1S1 STFTB1S1 OVB1S2 STFTB1S2 OVB2S1 STFTB2S1 OVB2S2 STFTB2S2
65 190 -7.8 0 2052 87 0.68 -14.8 0.1 N/A 0.82 -14.1 0.095 99.2
65 190 -5.5 -0.8 2038 87 0.065 -5.5 0.03 N/A 0.15 -2.3 0.075 99.2
65 190 -10.2 -1.6 2037 87 0.73 -3.1 0.08 N/A 0.825 -10.2 0.14 99.2
65 190 -3.9 -2.3 2068 87 0.59 -10.2 0.105 N/A 0.805 -9.4 0.14 99.2
65 190 -9.4 -3.9 2062 87 0.165 -3.9 0.045 N/A 0.65 -8.6 0.13 99.2
65 190 -8.6 -3.9 2068 87 0.155 -2.3 0.05 N/A 0.14 -2.3 0.075 99.2
65 190 -7 -4.7 2065 87 0.1 -1.6 0.035 N/A 0.055 0.8 0.065 99.2
65 190 -6.3 -4.7 1996 87 0.055 2.3 0.035 N/A 0.16 5.5 0.07 99.2
65 190 -6.3 -4.7 1996 87 0.055 2.3 0.035 N/A 0.16 5.5 0.07 99.2
65 190 -1.6 -4.7 2016 87 0.11 5.5 0.05 N/A 0.88 0 0.09 99.2
65 190 -0.8 -4.7 2042 87 0.845 0 0.13 N/A 0.62 0 0.38 99.2
65 190 -0.8 -4.7 2050 89 0.72 -1.6 0.18 N/A 0.145 6.3 0.115 99.2
65 190 6.3 -4.7 2045 87 0.605 -0.8 0.105 N/A 0.815 0 0.12 99.2
65 190 5.5 -4.7 2067 89 0.84 0 .12 N/A 0.835 0 0.245 99.2
65 190 -0.8 -4.7 2088 89 0.62 -1.6 0.275 N/A 0.44 3.9 0.655 99.2
65 190 -0.8 -4.7 2083 89 0.165 3.9 0.26 N/A 0.825 -3.1 0.795 99.2
65 190 -1.6 -4.7 2111 89 0.2 3.1 0.38 N/A 0.47 2.3 0.69 99.2
65 190 3.1 -4.7 2129 89 0.2 2.3 0.475 N/A 0.77 -3.1 0.5 99.2
65 190 3.1 -4.7 2112 89 0.77 -0.8 0.085 N/A 0.88 -0.8 0.11 99.2
65 190 4.7 -4.7 2149 89 0.83 0 0.165 N/A 0.315 3.9 0.215 99.2
65 190 0 -4.7 2171 89 0.815 -0.8 0.765 N/A 0.805 -1.6 0.715 99.2
65 190 3.9 -4.7 2192 89 0.845 -0.8 0.81 N/A 0.285 1.6 0.735 99.2
65 190 3.9 -4.7 2189 89 0.165 3.1 0.69 N/A 0.455 2.3 0.585 99.2
65 190 3.1 -4.7 2147 89 0.085 6.3 0.105 N/A 0.13 6.3 0.095 99.2
65 190 5.5 -4.7 2148 89 0.82 0.8 0.13 N/A 0.735 0.8 0.195 99.2
65 190 0.8 -3.9 2199 89 0.78 0 0.18 N/A 0.395 4.7 0.36 99.2
65 190 6.3 -3.9 2196 89 0.36 5.5 0.23 N/A 0.755 0 0.17 99.2
65 190 4.7 -3.9 2189 89 0.085 4.7 0.105 N/A 0.12 7.8 0.1 99.2
65 190 6.3 -3.9 2199 89 0.73 0 0.145 N/A 0.755 0 0.165 99.2
65 190 0 -3.9 2196 89 0.165 6.3 0.105 N/A 0.22 5.5 0.14 99.2
65 190 0 -3.9 2217 89 0.775 -0.8 0.215 N/A 0.87 0 0.735 99.2
65 190 -1.6 -3.9 2237 89 0.805 -2.3 0.77 N/A 0.745 -3.1 0.84 99.2
65 190 -3.1 -3.9 2227 89 0.1 2.3 0.64 N/A 0.065 3.9 0.535 99.2
65 190 -1.6 -3.9 2200 89 0.715 -1.6 0.735 N/A 0.855 -0.8 0.815 99.2
65 190 2.3 -3.9 2210 89 0.7 -3.1 0.77 N/A 0.77 -3.9 0.795 99.2
65 190 -3.9 -3.9 2178 89 0.075 3.1 0.15 N/A 0.68 6.3 0.12 99.2
65 190 3.9 -3.9 2205 89 0.83 -0.8 0.18 N/A 0.78 0 0.21 99.2
65 190 -2.3 -3.9 2228 89 0.58 -2.3 0.31 N/A 0.75 -1.6 0.75 99.2
65 190 -2.3 -3.9 2232 89 0.745 -3.1 0.75 N/A 0.425 -3.9 0.77 99.2
65 190 3.1 -3.9 2205 89 0.745 -1.6 0.36 N/A 0.175 3.9 0.13 99.2
65 190 -0.8 -3.9 2212 89 0.205 3.9 0.285 N/A 0.195 4.7 0.15 99.2