I have 2 valves out of 8 that have low water pressure ?
Check the flow control and see if it is properly adjusted.
Most brass valves have a + sign on the top. Open it all the way and then back it down a few turns.
Test your valve again and see what happens.
Plastic valves can range from a silver dollar sized round knob down to a quarter sized knob or with the Hunter Anti Siphon valves, they have a smaller size but come with and adapter handle to aide in adjustment.
If the flow control does not fix the problem, then you may have a diaphragm that is going out on you.
Some valves are cheaper to replace the whole thing and others may be cost effective to buy the diaphragm kit.
You could also have an obstruction in the mainline side of the valve or debris that is keeping the valve from opening fully.
Don’t forget to check for a possible break in the lateral line. A break hidden from view can give the appearance of low pressure too.