Misfire

[manuelduverge]

When I start my car it's all fine, once I start driving it starts to idle at 1.5k and feels like motor is working extra hard; smoke starts coming out the exhaust and flutters between 1.5k and 2k rpms making it a tough ride; I have changed the Distributor; spark plugs and wires; intake gasket; any ideas on what it can be; and also heard it can be in limp mode

 

[daperez13]

Is the CEL on?

It could be a number of things. Fuel, vacuum, electrical, an O2 sensor. Remove the cat and look through it. If you can't see through it or it's in pieces, you may have leaned-out the car. Check your spark, compression, fuel pressure.