2002 Acura MDX - Actin' Up!

[HipGrrrrl]

So, I have an Acura MDX (2002) that has about 222,000 miles on it. Last year we had the transmission replaced (after a spectacular failure on the highway - that was exciting!). Other than that, I think it’s all been pretty routine maintenance. It has been hesitating quite often while accelerating from a stop (in drive and reverse), but doesn’t do it all the time. My mechanic cleaned something which was “very gunky” and that made the acceleration issue better, but it’s getting worse again. However, my question has to do with an event that occurred yesterday morning. I was extremely low on gas (had about 1/2 gallon left in the tank), filled her up with premium, and happily went about my errands. After the gas station, I drove about five miles to a store and parked it while I shopped. Then, I started her up, drove about five miles to another store, parked and shopped. When I came out of that store, I started her up and she kinda lurched and stalled out. I started her up again, she lurched and stalled out. The same thing happened in reverse. I managed to get her into drive and went up to an empty part of the parking lot and drove around. When I would brake, she stalled. Slowly, she began to continue running when in drive and reverse - but with some significant lurching here and there. She would always lurch before she stalled. Finally, after about 15 minutes, she was running okay, so I thought I’d skip calling AAA and try to get home. I did make one stop, but kept her idling in drive while I waited for service. There was a noise coming from the engine that sounded like little tiny pieces of metal pinging all around - almost like popcorn, but without any “POP!” After about five minutes that stopped and I drove home - about 20 (at speeds ranging from 30 to 60 with some stops and starts) miles with no repeat of the issue. She has since started twice, driven about 30 more miles and seems to be the same as prior to the “incident”. No more pinging noises. What in the heck is going on??? Is it urgent I get her in to see our mechanic? Thanks for any thoughts.