i have a 1997 chevy k 1500 with the 4.3. last fall it developed a problem with not wanting to start when the temp was below 30 degrees. plugging in the block heater didn't seem to help. the only way to get her started was to pour a little fuel down the throttle body (not good for it, i know). thought it might be a fuel pump, so had that and the fuel line replaced. also had the injection system replaced but it still doesn't want to start. i have been to several mechanics and no one seems to be able to fix the problem. any thoughts? thanks.