92 sierra popping out carb

I have a 92 sierra with a 4.3L. it starts but pops out the carb. checked timing and it's right on the money. the motor only has about 10,000 miles on a factory longblock.any ideas on what it could be? sorry i'm calling it a carb when it's a throttle body.

I don't know if your allowed to answer your own post but I have gotten a lot of help from this site and thought maybe I could help someone who might do a search on this problem. After I posted I talked to a mechanic who said it sounded like an exhaust valve wasn't opening.I took off valve cover and one rocker arm bolt was so loose the rocker fell off the pushrod.I got back to him and thanked him and he told me to get a new nut because they are self locking nuts.I love this site and just hope I can help someone thanks.