VW Jetta - very hard starting in cold weather. 2.0 liter 4 cylinder?

Why is my 1998 VW Jetta hard to start in cold weather? I had the Mass Air Flow Sensor replaced; car runs great once it starts and gets warm, but it cranks forever before starting in cold weather, and runs rough for a few seconds, then it's fine. It has 2.0 liter, 4 cyl, manual trans. No dummy lights are on.... show more Why is my 1998 VW Jetta hard to start in cold weather?
I had the Mass Air Flow Sensor replaced; car runs great once it starts and gets warm, but it cranks forever before starting in cold weather, and runs rough for a few seconds, then it's fine. It has 2.0 liter, 4 cyl, manual trans. No dummy lights are on. Mechanic says it may be the throttle body or distributor.

Here are some related answers from recent posts:
Automatic Choke may not be working properly, mass air flow sensor might be defective. Are there any dummy lights on?

I had this problem on my '98. Hairline crack in the voltage regulator had the car stall / hard to start / no start often in the winter. Later in spring the car would die in the rain. I sprayed various ignition parts with water (coil, wires, etc) and the car died when I got the voltage regulator wet. It revived after sitting 10-20 minutes and drying. I replaced the regulator and have had no troubles since. The regulator is at the top of the dash near the wiper.
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