my softail has 100.000 miles now, when the engine goes to 2000-2300 rpm it tries to miss like were still cold and when I try to go faster than 70 mph I open up the accelerator full open but do not increase the speed. Any suggestion as to the cause, please.

 

If it has a CV carburetor check the vacuum piston diaphragm for a tear or hole in it.

 

I would start off by doing a leak down test. this will tell you how the health of the motor is. if the valves are leaking a bit then it will show with this test.
sounds like you might need a little valve work. dsv

 

What year and carbed or fuel injected?

I'm thinking it's fuel related, especially if it's carbed....

 

Could clutch be slipping?

 

When an engine becomes tired, or weak, the signal to the carb becomes less, losing it's ability to wick fuel up thru the jets, requiring a larger jet orifice size.
Perform a leakdown test, and compression test for starters.
Do not overlook the camchest area for any lifter/camshaft issues.
Scott