when l accelerate from a stop there is a point at which a violent vibration shakes the car. When l push the pedal further down the vibration subsides. at first we thought it was warped rims, but when we let it coast downhill at high speeds is does not vibrate. PLEEESE HALP!! l <3 my baby... O_O (we've changed the spark plugs and checked the wheels) ..??

Does it have an automatic transmission? If that be the case, there might be something wrong with a module and it is trying to start in a higher gear, and by stomping on it, you tell the car to lower a gear. If it is a manual transmission, maybe perhaps you have a warped clutch?

You car is old and it is crap. Sorry, but even Porsche is break down eventually. Sounds like a buggered transmission.

check the C.V. joints and the fluid level of the rear end that is IF it is an automatic If it is a 5 speed you may need a clutch and they are expensive and no fun to change in that car! But the car is worth it!

CV joints.

You may be running into the same problem l was with my 85 928. On the independent rear suspension you will start to get a lot of play in the CV joints, mine hit this at 160,000 miles. Like most the rubber boot is already trashed out, pull the axel towards the differental and fill it with grease. Try driving it now, if the problem lessens change out your CV's. Plus ensure your differential isnt dry.