2006 Pontiac Grand Prix Automatic 60000 miles
Have had problem before and took it to shop. They said it was a lose wire and they just put it back. Check engine light comes on, stays on, car doesn't accerate like it should, feels like the car is straining to go. What can this be and how do I fix it myself if I can?
Take the car to an autoparts store and get the code read (they will do it for free).
If the code was (for example) coolant temp sensor, then the sensor is bad or the wiring to it, since you mentioned a loose wire, it may have come loose again.
The connector could be broken and would need to be replaced.