So this morning I started my car and it stRted just fine . Drove it for a few miles . Then all of the sudden the engine light came on. It's half lit. Then my car started feeling forced like its struggling for power. It runs smooth in 1st and 2nd gear but as soon as hit 35pmh or over it starts to struggle and feels like I'm forcing it or I can't get power.

I turned the car off and sat for a bit then I turned it back on and the engine. Light went off on the Tachometer but it stayed on on he speedometer. Then it started doing the struggle thing again.

Any help would be appreciated. My buddy told me that it might be a misfire or I'm running on 3 cylinders .

 

Or it could be 'limp mode'.

 

My friends 2012 MC S just had the high pressure fuel pump replaced for these same symptoms you posted about.
Check to see what codes have been set to guide your diagnostics. Simple code reader that several auto parts stores will lend you will get a fair amount of info out of the engine ecu for us to help you with.

 

First what are the codes that came on with your Check Engine Light? Then we can go forward. There are a few things that would put your vehicle into a Limp Mode. Air inlet hose to the turbo could have popped off. Diverter Valve could have a torn diaphragm. HPFP. Many things. So get some codes and we can look into this a little more.

 

^This^. You're experiencing Limp Mode. Typical triggers with your car could be misfires caused by a faulty HPFP. Get the car scanned by a reputable MINI mechanic.