1998 GMC Jimmy

I have a 1998 gmc jimmy 4.3 6 cyc. Vortex 4wd. 180,000 miles. Ran just fine until recently It overheated on me so I put in a new thermostat and then a waterpump. Everything seemed ok. About a week later my service engine soon light came on. The same day it went out again then several hours later on again. It seemed to be running sluggish The idle acted like it was running low when idiling and it kind of sluggish through the first couple of gears then it ran fine. It got worse about a week later, so I bought new plugs not wires because they seemed to be okay.I put the plugs in and a new pvc valve. When done I started the car lset it run about 5 min. While recharging the air cond. Coolant. After that I took it for a test drive around the circle drive approx. One quater of a mile it seemed okay. Pulled in the drive shut it off in house for 5 min came back out started it up sounde a little sluggish, put in reverse then it died. Now it will crank but won't start. It's getting spark and fuel I pulled 2 spark plugs they were a little wet, but my frien had also poured a little gas in the carb. I don;t know what else to do help its my only means of transportation. Also before I changed the plugs I took it to auto zone to be put on the code reader just to be told my hookup didn;t work. Thank you hope you can help