91' LS400 Bucking on Freeway...

[Taylorious]

Howdy! 

(Long time listener, first time caller) 

I've got a nuts-reliable non-TRAC 91' with 154K on it, and she recently started a strange condition that I'd want to trouble shoot here with some knowledgeable members:

ISSUE:

Driving on the freeway at consistent throttle (1.2-2K RPM) the car bucks, every 15-30 seconds, once or twice. This is not as prodigious as other members have described when they're seeing major spark or ECM/ECU issues, but is certainly noticeable. Driving at sub-45MPH speeds does not induce this, or if it does, it's so minor that I cannot see it. Further, when in neutral and holding revs at a given RPM (3-2-1K), it doesn't duplicate the bucking feeling. NO C.E.L., and all lights illuminate on the dash when I cycle the key to "ON."

Theories/Possible Solutions:

Based on some other threads here, I assume this is a slowly malfunctioning M.A.F. I plan to test it using (this) method, and was curious if you all had any other feedback on how I might fix this otherwise flawless car. I won't CRC clean it, but reckon the first 'stop' is to replace it. From there, possibly T.P.S.? Any other ideas?

Thank you. Forums like these have been the backbone of what I've used to fix all my vehicles for years, and I'm real glad to see this is still here. 

[Taylorious]

RELATED THREADS (in order of most to least related)

1) "Best Aftermarket MAF" (guy seemed like he has the closest issue to what I'm experiencing) 

2) "91' Jerking at 45" (guy seemed to determine driveline issues. Tranny/Diff. I doubt my tranny is going, though I haven't checked it...)

[Taylorious]

UPDATES #1:

Car started throwing CEL codes, albeit intermittently. Driving conditions identical to description above. 

Tested shorting TE1 and E1 in Diagnostic Port in Engine Bay, and saw Code CEL 13.

"Intermittent RPM Signal #2"

To the research I've done, this seems to be an all-too-common code that's 1 of about 3-4 things:

- Crank Position Sensor Open/Shorted

- Mechanical System Malfunction (Skipped timing teeth)

- #1 or #2 Camshaft Position Sensors

- ECM/PCM Issue

 

MOVING FORWARD: Based on the fact that 1) My car drives and runs amazingly, except for the ever-so-random stutter or three at 40-60mph every 3rd-5th time I drive... and 2) the fact that the CEL is not staying consistently on, but comes and goes... but is getting more frequently... I'm going with electrical over mechanical system malfunction. 

Next steps are to test Crank Position and Cam Sensors with a MultiMeter, and then if they ohm out, test the lines to the PCM/ECU. If they're good, I'd have to go with problematic PCM/ECU, which according to Yamae/LSCowboy on another forum, seem to go bad often and randomly in these UCF10 bodies. 

Any advice moving forward?