white smoke, head gasket? fuel problem?

[NC300SDL]

Some background on the problem. I've had my '87 300sdl for almost 3 years. The PO had the head replaced. It has a "22" head. This car is my daily driver. Have had some problems, but nothing a little time or money wouldn't fix. I was on the highway running about 65 for 25 or so miles. I entered city limits and had to slow down and eventually stop at a redlight. Car started to idle very rough and act like it was going to cut off. White smoke billowing out of tailpipe. Light changed, I accelerated, car smoothed out, smoke gone. Next light, same scenerio. This continued until I got back to office. Car sat for a few hours. Trip home uneventful. Car was fine for a couple of days. Again after a trip on the highway same problem. Car was again fine after it sat for a couple of hours. Next day, out of town trip. 90 miles on freeway at 70-75. Car is great. Until I get to stalled traffic. Then rough idle, white smoke. It seems fine until I have to stop. 5 hour meeting. Car starts, runs fine until I stop. Next day car starts okay, but smoke does not stop. Got to office, stayed about an hour. Started car, white smoke until I started driving. If I have load on engine, no smoke. If I stop, smoke. Took car home and parked it. Drove other car for 3 days. Started car today. White smoke on start up that went away. Let car idle, no smoke. Took car on interstate for 10 mile drive. Returning home, stopped at light, some hesitation. Back at home, idle not bad, but white smoke. Reading here, it seems this is either a head gasket or a fuel problem. Coolant was low, but does not appear to be any in oil. Oil cap does not indicate any blowby. Cracked injector lines. #1 seems to make the car run quietier. Clacking not as loud. #2 seems to make no difference. #3 through 6 idle worsens when opened. What else do I need to do and check for, compression test?, pressurize coolant system? clean tank screen? changed in line fuel filter when this first started. Fuel did not seem to flow out of line like it did when I changed filter before. Thanks for any suggestions.