Hey everybody got a good question for you, my 1987 xj with a 2.5 liter 4x4 manual sometimes surges on the freeway, it slows down and then speeds back up and it does not do it all the time?
What would be an easy fix, I am going to replaced the fuel filter now but do not have my tools here in sac, ca to check fuel pressure, besides it looks like I am going to have to make or buy a adapter to the throttle body to check fuel pressure.
If it is not a fuel issue "which I think it is" does the crank sensor when acting up show the same kind of problem, that would be an easy fix rather than try and deal with the fuel pump?
Thanks again, Steve J

 

my exsperience is a cps will cause a miss or will not run at all,you might try and unplug it and back in.
I think fuel supply,o2 sensor,restricted exhaust are common with what you are describing.

 

I changed the fuel filter again, just changed it back in sept 08, and the thing only has 2000 miles on it after it was parked after a real bad over heating by the wife.
Had to rebuild the engine and that took about 6 months to get the money together to rebuild it, and right after I got the new engine in my daughter had to barrow it for the last 3 months.
So now I am here sac, ca changing things to make it run better and like I said I replaced the fuel filter and it runs great but it may have a problem with the tank, lots of junk in the filter, it was clogged.
Trying to get my xj back permanetly, "no one is driving my xj after I get it back", the wife got a new car and the daughter is buying a new car also when she gets the insurance money, after someone totaled her 03 camry, next month.
I can see the clearing from the trees, lol.
Thanks for the input.

 

I had a Throttle Position Sensor do something similar. Also you might try some Seafoam in the vacuum system. The combo of Seafoam and a TPS cured my 2.5L Wrangler of strange throttle problems ~ 90.00 for both a new TPS and a bottle of seafoam from autozone

 

You answered your own question... changing the fuel filter did the trick. You have lots of junk in the tank.
Just carry and extra fuel filter and the tools to change it. Eventually you'll get it all out.
Or drop the tank and clean it out. Not that hard to do. Just make sure it's near empty.
Mike