Your 95' Chevy 350 with very high millage started missing lost horse power and oil pressure power while accelerating down the highway also all the rocker arms are tapping and loose to why?

oil pressure problem with high mileage could be a clogged up oil uptake tube on the oil pump. bad oil pump. Check the timing belt, Most people don't change their when it is due,(including me). It should be changed every 60k miles. It could be that the motor is just wearing out. The car computer may have some information on what is happening. I am not sure if your vehicle has an obd-1 or and obd-2 link. might want to take it to the parts store, and see if they will run the test for you. most don't charge. they want to sell you the parts to fix it. You can buy a testor for it. I don't recommend it unless you are responsible for many vehicles. hope it helps. duboff