lean codes

[mattd424]

ok my sister has a 1998 cherokee straight 6 with 200k on it.it had alot of trouble codes in it the jeep shakes a little at idle and when driving it surges and if you stomp the pedal rpm go from 5k to 2k up and down not like a shifting but like the motor is dying it has codes for lean on bank 1 ond bank 4 and coolant temp sensor the sensor was replaced but it still does it.if you put seafoam in the tank after bout 20 miles it will drive good for a day or 2 im stumped its been in the shop 3 times 400 dollar range each time and still no luck any help would be appreciated thank you

[discnik]

Any chance you can post the codes ?

Lean codes can be caused by low fuel pressure and/or volume, faulty injectors, vacuum leaks, exhaust leaks, EGR valve, IAC valve, and a few I'm sure I forgot.

You can do an intake manifold vacuum check, should be 19-21 in. HG.
Fuel pressure @ idle should be 47-51 psi.

See if you can find a parts house that will scan the codes for free and post them here.

Good Luck

[mattd424]

ok i will try n get it down to advanced and get a printout