My 89 740 GL starts and idles fine, and when I rev it to 1500 rpms, and hold it there, it does fine. However, when I rev it to 2000 rpms the gage immediately starts to bounce down to between 750 and 1250 and back up to 2000. If I let off the pedal then it idles smoothly down to about 900. If I try to drive it, it does same thing as the engine seems to turn off (die)then a fraction of a second later turn back on again as the rpm gauge bounces, and upon releasing the pedal it goes smoothly to idle. The car has 295,000 miles and a very bad rear main seal oil leak. The new things on car include rpm sensor, distributor, cap, rotor, plug wires, and engine temperature sensor. Things that I have swapped from salvage volvo include ignition amplifier, knock sensor, and radio suppression relay, and coil. The OBD codes come up good except when testing throttle position sensor (TPS); I am supposed to get a 3-3-3 when releasing from full throttle, but I get a 3-3-2. I adjusted the TPS according to Brickboard.com, and still get that 3-3-2. Flame trap and throttle body are clean. I still get the bouncing rpm. If anybody can point me in the right direction, I would greatly appreciate it. Thanks!