GMC DOOR LATCH User Comment / Complaint

When slowing down to a stop, or turning the car loses complete power. no dash signs are shown during this process. starts up immediately if heat/defrost is not turned on or is turned off, let the car sit for a minute. this happens when defrost or heat is used or not used only happens in the winter when temp. falls below 40 degrees. every time i turn on the car. in the summer and spring if it rains the car loses power when there is any amount of water on the road, does not have to be standing water on the road new fuel pump, steering cylinder,clutch has been cleaned several times, battery and alternator have been replaced, hooked up to all electrical machines at several dealers and nothing shows a defect this has been happening for 2 years after the car hit 60,000 miles.