Ok when i stop at a light i have this lope but if i sit there for a few it will smooth out for 2 or 3 seconds then go back to loping at a constant speed it is smooth but if i try to give it a little gas it will buck like crazy but if i give it a lot it will smooth out and go like hell im sorry i didnt quite explaine it right 96 concorde

Make sure the EGR system is working. Sounds like the engine is running lean.

The problem could be plugged up catalytic convert it is related to tune up.One more thing fuel filter too. Check auto zone if they have anything to burn out catalytic.When you change with standard catalytic you will have code PO420 will be a headache!!!!!!!! 80% cars have this problem Think twice before doing anything.

Clean your throttle body and map/maf sensor. If that doesn't work you may have a bad iac sensor (idle air control sensor)

lope (lp)intr.v. loped, lop•ing, lopes To run or ride with a steady, easy gait.
need another description plz.

What you describe is a cylinder not contributing,This can be from a misfire such as a broken sparkplug wire to a broken sparkplug, If it was a vacuum leak it would lope at idle but not buck at high speed,

try pluging egr vacume hose fixed my problem also loped when going down road at steady speed. hope this helps

WEAK FUEL PUMP OR STOP UP FUEL FILTER.RESTRICTED EXHAUST LIKE STOPPED UP MUFFLER OR CATALYTIC CONVERTER.LOW ENGINE COMPRESSION.VACUUM LEAKS IN THE INTAKE MANIFOLD.BAD PLUGS.WEAK SPARK OR IGNITION .

engine runs smooth if giving more than idle pressure. It is when the motor is engaged with transmission at start the engine lopes and wants to cut off. If I press the throttle hard it takes right off. If I come to a stop I can put transmission in neutral to keep it from cutting off. This creates a shifting that is not normal and I'm afraid it is a sign of failure coming.

check fuel pump

***** is correct adn yoru issues are not a quick fix.. some sensor is acting up and /or computer is being told to do something .....get full scope done and dig towards cause that way