Help with engine noise and "clunk" on acceleration

2001 Odyssey EX, about 148k miles. Tranny replaced at 109,000 miles 2 years ago. No engine mounts ever replaced. This week my wife told me the van was "twice as loud" as usual. I cranked it up and l and there was a noticeable "rumble" and vibration coming from the engine compartment. I checked for motor movement and the passenger side mount was obviously broken, so I replaced it yesterday. The rumble is still there in park and in idle (sometimes, not all the time). Took it for a test drive tonight and I could make it produce a distinct "clunk" sound from the engine compartment if I accelerated hard and, before it shifted out of first, let go of the pedal. The clunk happens after the gas pedal is released. So in my minds eye I picture the engine torquing and then falling back down at the front mount. We did the two person test with my wife tapping the gas while in drive and I did see noticeable movement in the front mount, but she was not gunning it, nor did I want her to. So my diagnosis is a 65% surety that it is a mount problem. Since the van is so old, I'm thinking of just replacing all the other mounts to get back that smooth idle and quietness. Any other things I should check out? Could this be another tranny issue?

Any advice appreciated. Thanks!