8.1 MPI engine pulsing between 1000 & 1400 rpms

Crusader 8.1 MPI 496 appears to search or pulsate between 1000 & 1400 rpms. Lower and higher rpms OK, and idle speed OK. Seems to disappear for the most part with a load on, (i.e. underway).
Second issue: port tachometer upon initial startup needle slowly clocks to full scale high and stays there. Shut engine down and restart works fine. Hour digits disappear. 308 total time on engines 2005 vintage engines.

Appreciate your thoughts on these questions.

Thanks.

Problem 1 sounds like a bad Manifold Air Pressure (MAP) sensor. It takes only a few minutes to swap between engines and see if the problem moves. Problem 2 sounds like a bad ground on the tach. Either could be other issues, but those are simple places to start.

Further exploration of #1 (if it is not the MAP sensor) will require a MEFI-4 diagnostic manual. You can search for it on Google; the best down load I have found is on a hot rod site called Pirate 4x4. These controllers are a favorite of the hot rod community. With the manual you can find all of the likely causes and check them out with swaps. A more professional approach is to scan the engine, but that requires a scanner or a well equipped mechanic.

getting the manual as CaboJohn suggests is prudent....

I think problem #1 is more commonly labeled as "hunting"....could also be a flaky TPS....and that will "swap" just like the MAP...

#2 could also be the tach itself...too many variations available today...again, these can be "swapped" for testing.

gentlemen,
Thank you for your input, I will swap MAP and TPS and keep my fingers crossed.
Will do likewise on the tach but, if it's anything like my port VDO voltmeter, it's out of production.
Thanks again.

also suggest keeping good (detailed) notes in your log book and to do the swaps one piece at a time....while you are at it, it wouldn't hurt to ensure each electrical connector you have easy access to is pushed in tight...also, check the hose on the MAP sensor..