It started about half a year ago. At higher speeds (about 70 mph) it felt as if I hit a gust of wind - that type of drag. It progressively got worse all the way to the point where the car had hard time going and literally jerked when I stepped on gas. Check engine light came on sometime. I was told I had air in the radiator since there was a hole in it spewing antifreeze everywhere. Three days after new radiator was put in, the sputtering and dragging went COMPLETELY away - convincing me that it WAS the radiator. Also shortly afterwards my alternator went out and had that replaced.

About three months later it started again. Higher speed first, then lower and lower and then all the way to the point where one day we could not go over 10mph with gas floored. But the next day it ran better.

I took it in had full tune-up done, fuel injection cleaning, cat converter was checked OK. Ran great for 3 days. Today I felt the drag in high speed again. WHAT IS IT?

Sounds like trash in gas empty tank flush replace fuel filter.

The tank should be pulled and cleaned out. The sediment from twenty years of driving has probably built up and is clogging the fuel pickup. This is why your fix worked for three days. Hope this helps.