rough idle with stalling F'ed up

[Robie]

1993 3.3L v-6, always has the roughest idle, the rpms bounce all over the place, they die down like the engine will stall then immediately recover and really rev the engine, will happen a couple times before a complete stall, and restart, then stalls again, takes a lot of gas to get it going again. i was thinking maybe spark plugs or wires, or maybe a vacuum line leak somwhere? any suggestions.

also have a problem at around 40-50 mph the car just goes absolutely nuts, and stutters like crazy like the engine stopped working until i hit the gas and the car rocks till i get over 50 which it works fine, had it goin up to 90+ mph without a problem till i hit the 40-50 mph mark again, is this related to the stall problem? please help i have to take this car to school and cant afford to get a new one to get me there.

[Pico]

My car was doing something similar (not to that extreme though) to that last week and it turned out to be clogged and restricted fuel injectors.

[rixGAphx]

Your '93 has a different engine, FI system, and computer sustem than the later 3.1/3.4 V6's, so direct comparisons/corrections are difficult.

On a 13 year old car, the cause could be many things, and could be more than one.

For starters, read your engine computer's stored codes, using the 'paper clip jumper' method.

If it's been more than a couple years/30k miles, go ahead and change the plugs.
The symptoms you described aren't typical of bad plugs, but it will be easier to track down the actual cause if the plugs are known to be in excellent condition.

The catalytic converter is expected/intended to fail eventually, and one symptom of a partially-clogged cat is rough running at idle.
Take the car to Midas or other muffler shop and have them check the condition of the cat. They turn on the engine, and burn a small hole in the exhaust pipe just in front of the cat. If the exhaust sound changes, the cat is clogged. If no change, the cat isn't the problem and they weld the hole closed. This is usually a free test.

The idle problem is frequently caused by a bad Idle Air Control (IAC) or Throttle Position Sensor (TPS) on the 3.1/3.4.
I don't know if the 3.3 has an IAC.
But, these parts aren't cheap, and it's not a wise move to just throw money at parts in *hopes* that will cure it.

Also check the air filter and the inlet tubes to/from the airbox.

Vacuum leaks cause rough running. There is a vac reservoir under the battery on the later GA's, don't know its location on the '93. The tubes at and near it can become unplugged, so check and reconnect as necessary.

Good luck.
-Rick