98' Disco strange surging
 

98' disco with 120,000 chassis but 16,000 miles on new motor build. Sitting at idle after a 20 mile drive, world was at peace. Suddenly dies, starts right back up with a strange surging. Feather the idle it stays running. Dropped into drive and it acts as if the key is being turned off and on. To the beat of a drum steady, on off on off. Tach drops, power drops. Got it to 2k rpm and it took off like a rocket. second it drops down it starts all over again.
Into the garage and up with the hood. I have a rotted down running parts 98 in the yard as well as a cabinet of new parts on reserve. So here's the list as parts were changed.
Fuel was reading 31psi at idle. replaced with new delco pump. replaced filter as well because it was due. Dried tank and wiped out the bits of stuff. Now have 40 psi at idle... and the surge.
MAF removed, cleaned with crc MAF cleaner, still surging
replaced the MAF, still surging.
Idle air control
New Fuel pressure regulator
Throttle position
Downstream O2, bank 2
Air intake temp
Crank speed sensor
Plugs and wires.
Always dc the battery between changes.
Now have all this shiny stuff as an accessory to the surge. This is driving me insane and before I back this tea and crumpet British SOB into the yard and shoot it, Someone tell me what I'm missing.
FYI no codes showed other than O2 and multiple cylinder misfire.
I like to think of myself as the smartest raccoon I know, I hate to ask for help and I only get smarter by trial and error till something's fixed. I'm at a loss right now and it's too flippin cold to walk. WHAT AM I MISSING?
Thanks Rob

VSS or TPS? Do you have an ultragauge to see what the computer says is going on(MPH and Throttle %)? Are you sure the throttle position sensor you replaced is good?

Those are my guesses...

At this point I would say have your adaptive values reset by a tech and go from there. You've thrown socmsny parts at it there's no telling anymore.

I'm going on the assumption that all parts from donor are good since it ran fine in moving it to the garage.
I tried a systematic approach of one part at a time with the pump/filter regulator exception. But they were all new. My scanner will read most values in live mode but won't reset anything. Most of the stuff it reads is above my pay grade and it's hieroglyphics to me.
Closest dealer is 70 miles away and that's a hefty tow bill. Plus the giga-dollars they charge. If that's the last resort it'll go. Aggravates the hell out of me but I love her. Crap! I'm married to my rover...

I'd definitely check the vss for that multiple misfire as I'm dealing with that as well and my Innova scanner told me to fix my VSS and fuel pressure reg (you've already fixed the reg so try the vss) good thread on rebuilding your existing vss in the tech section) good luck. Sorry I can't shed more light into your frustrating situation.

Post the codes on here. It might be something simple like a coil pack. Is it surging or missing ? Surging sounds like a fuel problem, missing could be spark.

I hadn't even considered the VSS. In park idling when the miss and die started so I didn't think. Will pull it and try a rebuild but ordering a backup anyway.
As for the codes. P1193, P0158, P0300.
After reading about the the weirdness from a faulty VSS, it may explain a few other things. Honey, aka Honey Badger has never had the power she should even after the engine build. Strangely slow to downshift on the highway up hills, just random quirks.

Vss rebuild is def on my to do list. Never have the time always (happily) too busy playing with my son on the weekends or (unhappily) working.

VSS rebuild times 2 today, tried both with no change. Did however find something that seemed odd and is leading me in a different direction.
While I had the batteries DC'd I dropped a test light across ground wire to battery ground and got light. Ran thru all the fuses and finally found the source. It was the 60 amp for the window lift/CDL/rear blower motor. Is that right?
DC'd the fuse and still no change in the running side of it. But now in the closed garage I noticed how horribly rich it's running.
I have beer a plenty and will feed you steaks till you're tired if someone wants to figure this one out.
Seriously thinking about a honda accord right now.

What is the TPS reading key on?