Why service engine light is on after replacing EGR valve

I replaced EGR valve,it passed inspection& service engine light came back on OBD reads insuficient flow to EGR valve.

You replaced the EGR, but did you clean the passages? Carbon build-up will clog the passages and restrict flow.

The EGR is fed by a tube that can get plugged up. Fixing this problem can be deferred until your next emission test…On older Fords, the EGR tube can be difficult to access. On newer models, it’s fairly easy…It’s not a critical issue…

sprayed cleaner into vacume tube more than once. Do I need to take valve off and spray cleaner inside EGR valve or keep putting cleaner in?

The vacuum side is not the problem. It’s the FEED side that gets plugged up. What engine are you dealing with?

In addition to the passages you have a control solenoid and a sensor (DPFE sensor). The problems with Ford’s DPFE sensors are somewhat legendary. A repair manual will tell you how to test the solenoid and sensor. (It will also tell you how to test the EGR valve btw which was probably not bad to begin with).