i recently purchased a 1989 Cutlass Ciera for $500
its a one owner car with 101,000 miles very well kept

the car starts and runs for a few minutes but after it gets warm and i try to restart it it will not start! then when it gets cold it will start again,

when the engine is running you can hear the RPM's increase and decrease by itself,

when the engine is running and i step on the brake pedal the oil pressure goes down and makes the engine to stall, and sometimes makes it shut off..

any help will be appreciated

engine is a 2.8