yesterday i decided to blow out my heater and flush my cooling system after work. as i pulled out headed home.. it drove fine. but about 4 miles away it started sputtering. it would run, then cut out for a split second. eventually it died, i checked under the hood to see if something came unplugged but everything seemed fine. when i went to see if it would start again.. it did and i made it another 3+ miles before the same thing happened. started up again and i made it home.
now today i went out and started it right up. it idles perfectly fine in neutral, park and mostly works in reverse, but not always.
yes the engine light is on and no i have yet to hook the scanner to it as it is at work.
i found on here that there is a good chance it is the ECM. i'm just curious to know if there is any tests i can do to verify this before i drop the money on something i can't return.
any help would be appreciated. i'll get the light figured out asap but theres no promises how soon. its zero degrees outside and.. well.. **** that lol

 

also, forgot to say this... after i started it up today, it wants to die as soon as it goes into drive.. with my foot on the gas it goes but it cuts out every two seconds or so.

 

People replace ECMs a lot, but they rarely fail in my opinion. It would be my last suspect, not the first.
You definitely should check the error code before going any further. You should be able to do that by shorting the A-B terminals of the ALDL connector. Then turn the key on and it will blink the codes. Very likely you just lost a critical sensor - a bad MAP for example can cause terrible drivability because it wouldn't be able to sense the load.