Engine dies when car comes to a stop

I Replaced my a/c compressor with a new one,
added 7oz. Oil, brought to shop to have it
A/c serviced, blows cold, but when I come to
a full stop engine dies, I call the shop up
they told me that I possibly have a bad engine
load sensor, & for 75.00 fee +parts they could
fix the problem, if I knew where it is located,
I could do it myself
Can anyone help? Thanx in advance