engine vibration(im a newbie)

Ive been reading posts on this site for a month and you guys are fantastic at giving advice so,I have a problem and maybe you all can help.I have a bad engine vibration from 1500rpm to 2700rpm,changed plugs,cap and rotor no help.I purchased this vehicle after the previous owner couldnt get it running after having driven it with old gas in the tank(2yrsold).I have replaced the fuel pump,filter and the fuel pressure regulator,and had the tank removed and cleaned out.Do I need to replace the injectors or could this be a sensor? Thanks all

vibration, you check your engine mounts? or maybe you are not describing it clearly.

vibration, you check your engine mounts? or maybe you are not describing it clearly.

It seems as though there is a cylinder not firing.Ive done all checks to make sure spark is at the plug on all wires but its very weird,the vibation only happens at 1500rpm well maybe a lil sooner on up to 25-2700rpm at 3-4500rpm no problems,engine spins nice no shakes at all.

I would look at the injectors, they can be removed and checked, or try running Marvel Mystery oil in the gas tank, that will clean out your injectors and valves. I sounds like the injector(s) may not be spraying the fuel right due to build up from sitting so long.

Ive gone trough and pulled the spark plug wires one at a time while its running,and it seems as if #5 and #6 cylinders are not hittin with full power especialy #5.

i would suggest a compression test.thats probably the most basic thing,make sure the engine is capable of running right.how many miles?

The engine came from a donor vehicle(wrecked) Im not sure but the person I bought it from(ex inlaw) said he purchased engine and was told (use to have paperwork)25-30,000 miles on it.Now how long that it sat before it was put in the current vehicle im not sure,but the only thing leaking from the motor since running&driving it is the blasted valve cover and Ive put a few miles on it already.I'll do a compression test on it asap!