It started overheating so I replaced the thermostat now when I start it it vibrates and shakes and acts like wants to back fire but doesn't. It runs real rough till RPMs get up then kinda levels out but can still tell its not right

V-6, standard 2 wheel drive

While changing t-stat .. did any coolant spray/splash onto coil pack or plug wires? .. Check engine light on?

Check eng light yes the auto store puts on there computer it shows crankshaft pos sensor, cam shaft pos sensor, lean/rich bank 1 & 2

More complete testing with better scan equipment required!

So no idea?

Parts store test results make no sense! .. Lean/rich condition present at same time? .. That's the reason more 'qualified' testing is required.. To try and offer even a guess based on information received would be moot.. Sorry.