Jeep won't start (ignition)

Guys help me out here. I have a 90 XJ with the inline 6. I have a ton of new ignition parts on my rig and I am about ready to pull my hair out. The start act like it wants to engage but doesnt turn the motor over so you hear this "thud" Starter is bolted up correctly and all lines are attached correctly.

New Items:
battery (Optima Battery)
starter (siliniod built in)
battery cables (Cleaned grounding locations)
ignition switch
lock and key

I am about read to torch the jeep

First of all, if it won't turn over the problem isn't ignition. It's starter or starting circuit related.

Beyond that, it's hard to tell. You're certain that current from the new battery is getting to the starter? Have you had the starter bench tested? New parts can be defective, you know. I got a replacement alternator that was totally dead on arrival.

Next question is, was it running before? Is it possible the engine is seized? Try removing the spark plugs and turning it over by hand with a socket and breaker bar on the harmonic damper bolt.

I am sorry Eagle I guess I didn't eplain everything fully.
it starts and runs great form time to time. I can go 2 or three days with it working great then bamm it act like its not getting enough juice to the starter to trun the motor. Yet I thought the same thing on the starter. I thought bad solinod so I took it back and got another new one (lifetime warranty). The only thing that I can think of the starter relay that is up by the battery. thats the only thing I havent replaced

it sounds like you have an internal starter problem intermittently.