How much does it cost to do a valve job on a 1990 4cyl jeep wrangler

old old jeeps..... which engine, the 4.0L inline 6? why not say ?
well here are the proper linear steps.
1: fuses good battery charged, and cranks robustly.
2: compression over 150psi, WOT. if not fix that. ?
3: spark strong to all cylinders not just 1.?
4: spark timing check show its still firing near 0 TDC.
5: at the point in time, it will run on test fuel for at least 3 seconds.
does it, feel better now? that you can see it run?
if not the CAT may be melted and blocking engine exhaust 100%
6; and last is fueling (the ECU cuts fuel or 3 reasons, )
dead cam/crank sensors, or dead tacho line.
7: ok check fuel pressure next.

i skipped the all important scantool because we dont have one
1988 to 92.. (not until 1993 do they work OTC tools)

did you do the magic key on off test>/
?
keyon 3 times, might work on latter 92s.....
http://www.fixkick.com/Jeeps/jeeps.html#poor_mans-scan

the crank sensor is tricky to replace.
its not just jammed in a hole.
did you read the FSM Book first. before touching it.
some have a paper sticky tape on the end (jeeps do)
and when you start car first time, the tape flies off getting that critical gap correct. (pure magic no?)
if not done right, you now have 2 problems.... not good that.

It sounds like your firing order is out or your timing is out or you have fuel starvation.
I believe the firing order is 1-3-4-2 on your car. Only English Fords had a firing order of 1-2-4-3 and VW beetles are 1-4-3-2.
Next. check the timing. You should have a spark on no 1 cylinder when the timing mark on the front pulley is about 16 degrees from top dead center - there is a mark on the pulley to show these positions. If you don't know how to check it, take it to a service agent.
Make sure your fuel filter is clean - replace it, they are cheap - and then make sure you have good fuel flow to the carburetor.
Finally, you could have burnt valves. This will mean taking off the cylinder head and reseating or even replacing burnt valves. This could be a costly job and should be done by a qualified technician.

Need to check spark and fuel start by picking up a tester for the wires it plugs in like a spark plug and has a light that will come on if you have spark the next disconnect the main fuel line to the fuel rail and turn the key to the on position if u get fuel out of it the the pump is good

try changing your spark plugs....

Start by checking spark plugs, if only one of your spark plugs are not in optimal conditions your cylinder will miss fire causing the rough idle.

It sounds like you have a bad valve or a cylinder isn't firing. Pull the spark plugs and check them for deposits and clean, regap or replace. Do a compression check of the cylinders to determine if you have a problem with a valve.

cylinder number 2 has a misfire

You need to find out if you have spark there, if injector is working and if the cylinder itself has good compression. Then, you can work backwards to find out why whatever is "missing" isn't there.

bad fuel pump can cause this or plugged fuel filter but i believe they are one unit

What engine?