need help

ok i have a 88 comanche with a 4.0l(needs rebuilt, has a little knock but still runs) rebuilt ax 15 np 231. theres a 3.5 " lift on it with a crossmember drop 1"... unknown mileage but i know its a lot...so i am having a couple problems with it and was wondering if anyone else can help me figure this thing out... ok so first thing is the idle is really rough but sometimes itll idle ok but usually goes into the rough idle not sure what that is?? 2nd i have bad vibration when i start it... i can push the clutch in and it will go away... also it will go away when the clutch is let out if i play wiht pushing the clutch in and out... this also happens when driving has happend in every gear and same symptom play with clutch and will go away! i am planning on building a motor for it i would hate to do all that work put the new motor in and have the same things happen does anyone have any ideas about this thing?
and one more thing it kinda off that subject but the brake poportioning valve that is activated by weight can i just bypass that thing? cuz somehow that thing broke one of the diffcover bolts clean off(because thats where the load sensing bar attachs to)
Any help is greatly appricated
Thank you
Justin

What condition are your vacuum hoses? Check the line going to the MAP sensor on the firewall, had a small crack in mine once that cause bad idle. Check the "boot" from the air cleaner to TBI, mine cracked once causing a bad idle. Clean the IAC. Start there.
Not sure about the vibration, not knowing condition of truck, clutch, motor mounts, etc., sorry.
Brakes:http://www.comancheclub.com/forums/...235043&hilit=bolt+proportioning+block#p235043
just one of many threads dealing with this.
That will give you a start.

The previous post mentions motor mounts. I would definitely check them and the tranny mount to start.
When I replaced the worn ones on a previous XJ I had, the difference was amazing.
Both my MJ and my current XJ need replacements soon.