Hello, I recently changed the spark plugs, wires, and distributor cap in my 2000 Chevy blazer 4x4. Now on a cold start it is clearly underpowered for the first 20 seconds or so after shifting out of park. After that I don't notice any differences in the city or on the highway and haven't gone far enough to measure fuel economy. I've driven about 30 miles and no check engine light so far. Any insight would be appreciated. Thanks.