cherubkey

Hi!

I just purchased a '99 Sport, 4.0L, standard transmission, with 120k miles and after taking it on a road trip I noticed some trouble. After a couple hours of driving at 75mph the engine would sporadically lurch (shudder). It seemed to get progressively worse, but after stopping for an hour or so it was fine until another 2 hours of driving at high speed when it started again. The same thing happened the next day driving back home.

It never stalled, but seemed like it would if I had run it long enough. Also, it seemed to lurch more when I was giving it some gas (like when I started to go up a hill). The 'check engine' light came on during one of the lurches, then went off over night, and came back again the next day with another lurch. To further add to my confusion, I got off the interstate during a time when the engine was lurching and as I coasted to a stop noticed my engine was running near 3k rpm in neutral. I tried lifting the gas pedal, but that wasn't the issue. Within a minute or so it came back down to 1k.

Incidentally, my cruise control doesn't hold its speed, and my blower will switch from the upper vents to the defrost vents depending on what speed I'm traveling. It seems like when it's under load the vents switch to defrost, and then back again when I've let up on the gas. Also, with the blower off, when I give it a lot of gas to get up a hill there seems to be some air coming in the defrost vent, while at normal speeds there is none.

This thing sure has personality! If you can be of any help explaining what might be going on it would be greatly appreciated. Thanks much.

jd4x426

have you done a tune up on it might just be old plugs or coil something of taht sort i would start there if it doesnt help you at least have the peice of mind that your ignition system is up to par also try cleaning yoour iac and the tps they have a hand in idle and will act up if they are all gummed up