Engine cranks, but does not start at times

First of all I've had the battery replaced, some cables that connect to the battery via a dealer that were exposed as well as the ignition/cylinder switch (?) Sometimes the truck will start with no problem other times I have to press on the gas for it to start. All of the lights, radio, clock etc. Come on. There is no grinding sound nor is it slow to turn. You hear a click as if it's trying to connect but won't. Until I press on the gas. This has been going on for some months now, the replacements have taken place during this time. I have been online searching for suggestions, I have heard that the starter and/or relay needs to be replaced, spark plugs and even fuel injector cleaner. What do you suggest?

Thanks for the prompt response. What do you mean when you say to have the fuel pressure checked? A diagnostic was run on the truck twice, once by the dealer another time by an O'
Reilly's. Nothing was ever found and I would expect it to be surely found by the dealer.

Okay I'm assuming that the mechanic will know what a 'tol' is? And that it has to be 'dhooked'? Not being funny I just want to be able to go in and give him clear direction. Is this something that a tune-up would correct?

Have replaced battery, fuel pump, cam and crank shafts. At wits end.

Won't turn over

Engine Mechanical problem
2003 Jeep Liberty 6 cyl Four Wheel Drive Automatic

the jeep died on my while driving cut off will not fire. I have replaced both the cam and crank sensors. Coils are sparking. Getting fuel to the rails. It could have jumped time. It turns over but will not start any ideas on where to look and what to try next.

My car won't start. Battery had a lot of corrosion on it. Cleaned it good, still wouldn't start. Original battery. No noise when I turn the key. Lights and radio work good. Tried tapping the starter and still didn't start. Is it the battery? Is it the starter?

Car wont start but lights are on on dashboard and when I try to start it I hear a clicking noise. Could this be the battery that has gone dead or can it be something else. Power locks doesn't work either I have to lock them manually.

Engine Performance problem
2002 Jeep Liberty 55,000 miles

I had never had any problems starting my car until recently when it began -- every once in a while -- not to start on the first try. It used to happen once it a blue moon, but it is getting frequent, almost daily. It never happens when you've already been driving that day. Usually the next morning. No weather problems, as I'm in a warm climate. The battery is relatively new. Is it the starter?