Hi yall I'm new and im having issues tracking down why my 93 cherokee is giving me a hard time I've replaced the rear temp sensor,air intake temp sensor,idle air control valve,throttle position sensor and crankshaft sensor I replaced all that over the weekend and it got a little better but it's still hesitating when it starts then once it gets warmed up the engine seems to gradually lose power bogs down and kills itself. It wont start back up for a couple hours and when it dies there's smoke coming out of the throttle body I'm stumped any advice would be helpful tha you

 

Everything you said having been done sounds good. Except possibly for having replaced the Crankshaft Position Sensor (CkPS)? If it is an aftermarket non-Mopar sensor, this could explain the stalling and heat related crank-no starts. Was it doing this same type of exact thing when the other old CkPS was still in there?

Being down on power like that with noticeably poor running conditions makes me concerned about internal engine condition. Specifically, for with the piston rings not seated/sealing well enough, and excess blow-by. If pressure is getting lost past the pistons you could easily have a loss in excess of 20-30+ horsepower. It could maybe explain the reason for having seen the throttle body smoke too, but I am not totally sure?

You can test for blow-by by using an engine blow-by meter attached to the crankcase vent on the valve cover breather (CCV), or PCV (but I do not think your Jeep has a PCV?).. either way, they do essentially the same things. When the engine is running, all blowby that leaks past the rings will flow through the crankcase, out the valve cover opening and through the blowby flow meter sensor for a reading when testing

A blow-by flow meter can tell you precisely how much blow-by is occurring inside the engine. Unlike a compression test or a static leakdown test, a blowby test actually measures the volume of gases that are entering the crankcase past the piston rings. I would want to do a compression test on the engine too though...

Check the CCV (or PCV if that is what is in there?). If it is not right and working, or clogged, there is no way for the piston ring blow-by to get out of the crankcase, except through the throttle body.

Pull all of the spark plugs, and look for any that are looking very different from the other ones. If they are too clean, or too dirty.

How does the oil look, normal? Are you down on oil, or have you seen losses of coolant?

 

Might wanna check your fuel pump, check pressure or when it dies and won’t start try spray brake clean in the throttle body see if it starts back up.

 

Have you checked your catalytic converter. Your general symptoms sound like the cat is clogged. When it gets very hot it will completely close causing back pressure stalling the engine. It will then release that pressure through whatever valve is open when the engine dies causing the smoke from the throttle body.
​​​​​​when you get it started check the exhaust pipe to see if you have good exhaust flow. A good trick is to drill a hole in the exhaust pipe about a half inch wide just before the catalytic converter. This will allow the exhaust to escape their and not cause back pressure.

 

Also true,hooking up a simple vacuum gauge and watching vacuum when accelerating can tell you if a cats clogged. I believe vacuum will go down while accelerating under load if I'm not mistaken,