My son just recently purchased a 1991 740 non-turbo. The car ran great for the first few months and now has a real hard start when cold. Ater the temperature gets to about normal it will stabalise but when you drive it and try to accelerate from a dead stop it misfires and looses all the power. Also if it's just idleling on park and you accelerate it will do the same thing on about 2,000 rpms. It bounces and will not go over the 2,000 rpms. We have replaced the fuel pump, the dist. cap, rotor, spark plugs, the temp sensor on the radiador. It also has another issue not sure if related the speedometer will sometimes jump to 30 mph and stay there while the car is on park. we replaced the sensor but it still does it. Any ideas or suggestions?