weird slipping/resistance feeling when accelerating

1st gen with 130K, just started a few days ago, almost feels like it's slipping when I accelerate, also have noticed an occasional loud bang when going to pass someone, almost sounds like a backfire but it's not. Any ideas on where to start looking?

 

Fuel filter
Transmission

 

Stick, or slushbox?

Stick: Slipping can be caused by the clutch or some of its components. Banging/chattering same.

Automatic: Slipping sensation can be cause by low fluid, or the torque converter may be going bad. Banging may be a hard downshift? Can also be a result of low fluid.

Other possibilities for the banging include worn engine/transmission mounts, worn center bearing, loose leaf spring U-bolts, worn out leaf springs, etc.

 

automatic, happens in 4wd as well, tried to diagnose tonight and struck out. It may have to go in a shop, my garage is full of remodeling crap right now. fluid is fine in trans, banging only happens on hard downshift when I mash the gas pedal on the freeway. Leafs are fine, the banging has always happened, just not as much as recently.

 

How do the engine & transmission mounts look? A broken mount can make a thumping/banging noise when you get on the gas.

 

Bad plug or wire, bang sounds like unburned fuel igniting in the exhaust system