Here's the scoop - got a buddy at a shop who installed a long block as the previous one failed - detonated #5.

New long block installed - still a dead miss on #5. Pop tested the injectors - all drop the same amount on the pressure gauge. Had a previous post concerning the timing procedure - it's a MEFI 3. No matter whether your in service mode or not - if you move the distributor - the timing stays the same. The factory service manual says to install the distributor, point it to number 1 - and move on. Seems kinda odd - but on the MPI - that's what it says. Checked the injector feed with a noid light - it pulses as usual. Compression is good, ignition is firing - any ideas????

You have compression fuel fire and exhaust do the injector test with a tester with the injectors pulled to see if it puts out a mist or a stream. The dist you need to set as in the book to no 6 maybe there is a arrow in the dist if you are one tooth off it runs like crap. The timing is set by the computer so if you dont follow the instructions crap in crap out. Then check your spark at the plug with a good spark tester. let me know if you need some more help I think I have a book around the house or i can fax from work.

You have:

verified compression w a gauge?
visibly checked spark on the same plug that has been running in the hole?
swapped injectors with a nearby one?