What could cause my 89 XJ Limited automatic to stumble, but never stall out, for 3 or 4 seconds maybe a couple times each day? It usually happens when stopped, but not necessarily, and each time the radio loses power for the exact 3 seconds of stumble. The other stuff in the cabin doesn't lose power. It idles like a dream otherwise.

As a side note, I do have a long crank issue that's almost certainly a check valve issue or leaky injector. I also basically ran out of gas accidently a week or 2 ago, before the stumbling began.

Any ideas? (please don't reply with platitudes about doing cruiser54 tips. They're great and and all, but I've done them and my XJ is in excellent overall condition.)

Many thanks in advance.