Liberty with no power

[carjimost]

I have a Liberty 2004 and I'm having problems when it gets warm at first it starts failing like a spark plug or current issue cause when I accelerate it rummbles a little but it gets worst when it goes warm if I press the accelerator the speed does not increase It decrease and if I loose the accelerator a little it speed up a little but rummbling, I take it to the shop for a Scan and they told me that only P0172B and P0175B codes appears so then they replace the coil but the failure continue now do you have any idea what can be happening.

[sevenslotgrill]

coil packs are possibly bad. You should take it back if they replaced one and it is still doing it.

[wayneo69]

sounds like a 3.7L tell them to do a compresion test and a leak down test vaulve get pitted pretty bad on the and so do the vaulve seats in the heads also have them check the o2 sensors properly to make show the are switching