93 Bravada Issues

hey guys i have a 93 bravada. i crank it and it starts but it does not idol smoothly it vibrates the whole truck. i did a complete tune up including new battery, Spark plugs, spark plug cables, ignition cap, rotor. after i did all that i still had the same problem so the owner before me gave his mechanic which worked for oldmobile and told me thats it is the fuel pressure regulator. so i replaced the fuel pressure regulator, the intake manifold gasket, egr valve gasket, and cleaned the egr valve. when i did all this it worked perfectly. like 30min later my dad and i took it for a test drive and when we made a u turn to come back home it started vibrating again. It also read high oil when i first bought it like a week and 3 days ago. any advice????

It's likely either the fuel supply or return line is cracked.
Either purchase a fuel pressure tester or take the manifold top back off to expose the fuel lines, turn the keyswitch on then look for a leaky line.
It's likely your oil is deluted with gasoline, I wouldn't start the engine until this is fixed then change the oil or risk crankshaft & bearing damage.