Toyota Camry stalling issue?

I have a 1993, 4 cylinder, automatic, toyota camry. recently I had a friend of mine replace the head gasket because it blew. Since then the only trouble I've been having with the car is that it stalls after I floor it (if I have to get up to speed quickly, not necessarily putting the pedal all the way down). After i floor it it will start jumping, like it's out of gas, when I take my foot off the gas pedal. Once I stop or have to slow down the RPM's just drop and the car stalls. I can't get it to start in neutral after this, so I have to stop the car and turn it off then back on, then it will run fine again. If i let the car slowly get up to speed instead of flooring it, it won't stall. I've checked the vacuum hoses and they seem fine. What could be causing this?