Missing badly all of a sudden

Went down to philly today to a class and to take a family nite out. It ran flawlessly all the way down and most of the day. Stopped to pick up my daughters boyfriend at Temple, shut the jeep off, put the 4 ways on and waited 15 min for him to come down from the dorm. Started it up and it started fine and ran normally for about 20 seconds then got this horrible miss. We cancelled the rest of the nite and I managed to get it home, 94 miles.
Low idle miss, very little power till about 2,000rpm, still missing, can feel it thru the stick shift but the tach is steady, oil pressure is 50, temp is normal a hair below the centermark, voltmeter is normal at 14. In 4th gear at ~2500rpm the check engine light starts flashing, does not stay on just flashes till I get it back to around 2200rpm, does it in 3rd and 5th when I go above 2500rpm. When it started I popped the hood and saw no problem, check connections, no smoke out the tail pipe.
I managed to get it up here and just dropped it off at my buddys shop, did 55 all the way up the turnpike, and will look closer in the morning. I did not stop at the house for my OBD scanner so I have no codes to look at. This is just weird that it started all of a sudden... any suggestions ?

Do later XJ's suffer from the 'bacteria' or disintegrating fuel tanks that the ZJ's experienced? The reason I ask is because we had a '98 Grand that we bought new, maintained meticulously, and at about 60K, developed an appetite for fuel pumps. I've heard horror stories of multiple replacements, usually at over $1000 per. The one that failed on us thankfully died in front of my garage, so we pushed it in and dropped the tank. But afterward, kept throwing various codes, and often ran like shiite when the light was on. Dealer was no help, tried blaming Sunoco gas. Gas dealer said it was plastic tank breaking down. Bought a code scanner and kept it in the car-somrtimes left it plugged in! Dealer asked if I cleaned out tank with Clorox. Can an organism live in gasoline? Anyway, just a thought. Keep us posted on the outcome...Ray

heyhar said:

Do later XJ's suffer from the 'bacteria' or disintegrating fuel tanks that the ZJ's experienced? The reason I ask is because we had a '98 Grand that we bought new, maintained meticulously, and at about 60K, developed an appetite for fuel pumps. I've heard horror stories of multiple replacements, usually at over $1000 per. The one that failed on us thankfully died in front of my garage, so we pushed it in and dropped the tank. But afterward, kept throwing various codes, and often ran like shiite when the light was on. Dealer was no help, tried blaming Sunoco gas. Gas dealer said it was plastic tank breaking down. Bought a code scanner and kept it in the car-somrtimes left it plugged in! Dealer asked if I cleaned out tank with Clorox. Can an organism live in gasoline? Anyway, just a thought. Keep us posted on the outcome...Ray

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You're freaking me out, I just put two tanks of sunoco in this week, first time in about 3 years, before that I used sunoco as a steady diet..

All I ever use is Sunoco- it's a PA company that uses 100% domestic crude- even back in my motorcycle days. Remember 100 octane '260'? Anyway, my '92 has a steel tank, and with all the other maladies I've suffered with this car, fuel contamination or degradation has not been a problem, at over 182K. Your problem sounds electrical, possibly a sensor, spark plug wire, funky distributor cap, etc. How about mice or squirrels chewing wires? A fellow I worked with has a '01 Toyota Tacoma. Starts up to go to work one morning, gets about a block from home, and the dash lights up like Saturday Night Fever, and it dies in the middle of the street. Two days and thousands of dollars later, the dealer found the chewed harness to the computer. I hope it's a ten dollar part, but........

Problem sounds like a bad sensor or vacuum leak. Latter is easy to pin point or rule out. Codes might give you a hint...