Hi. I am new to the site and hope i can get some help from you guys.
So i have a 1998 xj 4.0 with about 185k (i know its alot) i have had the jeep since the spring and it has ran like new since. the other day i went to crank the jeep after just cutting it off and it wouldnt start. no turnover or any thing. i got pecked the starter with a hammer and it fired right up. well after letting it sit i drove it around and i noticed it would bog down and then the throttle would surge. well it quit the whole surging thing and now it is just bogging down after pulling out and while trying to maintain a cruising speed. i have to let off the gas and let the engine catch back up it seems It also idles rough at a stop while in gear. however it only does this once during the whole drive. idk if the surging, and not starting is related but now the only problem i am having is it bogging down.i have read countless post and found no problem is quite like mine but they all point to iac tps or cps. oh and i had the codes checked none where thrown. any advice is greatly appreciated, thanks

Start by checking the fuel pressure at the fuel rail with a mechanical pressure gauge. The pressure should be around 49psi.
Welcome to the forum.

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Okay it was around 49 and thanks by the way

Look for vacuum leaks to start off

Check that the O2 sensors are good and that the wires are not shorted out. Here is a picture of the fuse to check for O2 sensor. Also, Check for a cracked exhaust manifold. It will look like a small black hairline crack. Ususally very small and easy to miss.

Ok I got it fixed. I took a hammer and banged on the cat for a while now it drives fine. Been driving all day. Thanks for you help guys.

You need a catalytic converter.

That's beside the point.

Y'all know how much a new exhaust system would cost me? Any suggestions? It is a daily driver and I was wanting to know what some options were.