Mark LaSorsa

I have recently replaced the lifters on my 4.0lt. In doing so, the intake manifold+ vac lines were left in tact. after reassembly the engine will not idle it races to the point I have to shut the engine off quickly. I have replaced the MAP - no change. if I disconnect the MAP, engine will not start. disconnedted the Throttle Idle air control - engine races . cut off all air to the throttle and still engine races. not sure where else a vacuum leak can be coming from ,

dzywicki

You obviously have a major air leak somewhere. When I replaced the head on my '99, I had the same problem, but I had removed the intake manifold. It sits on little guide dowels and I kept missing it. It looked like it was lined up correctly, but was actually sitting on top of the dowels instead of being located on the dowels. If you removed the exhaust manifold, you would have had to remove the lower manifold bolts and the intake manifold could have moved. If you can't find the leak anywhere else, I would double check that. It took me 3 times to figure it out. I finally test fit it and then then looked at how far below the head surface it was when I finally tightened it down.
One tip for getting the manifolds back on without losing your mind. Put the lower bolts in enough to get them started. then you can tilt the exhaust manifold a little to slide it in. If you try to start those lower bolts blindly, you'll never get them in.

Cummins93

Look up a boost leak detector. It can be made with a valve stem, PVC pipe caps and rubber connectors in the plumbing section. Clamp it on the throttle body and pressurize the system. You will find your leak. If it's harder to find get a length of rubber tube hold it up to your ear and use the other end as a stethoscope to find the leaks....or buy a Harbor freight stethoscope.