1995 F355 Spider 6 speed manual, 22,500 miles, recent engine-out major done. Check engine 1-4 light comes on after car warms up and is at idle @ 1000 rpm. Check engine 5-8 light does not come on. Oil pressure indicates about 65-70 psi at idle. When given a little throttle up to about 2000 rpm, oil pressure goes up and the the light goes off. This does not happen when driving the car, only after idle for approx. 10 seconds or so. Car seems to run and drive normally otherwise. Any ideas?