Coil didn't solve anything. Checked all spark plugs and they look decent. One did smell like fuel, so I'll look into that plug and plug wire more later.
Bigger news: I put the Suburban to work and got to tow something!
I've switched over to working on my 1970 Datsun 510 lately. A common suspension modification involves switching out the front struts for beefier 280ZX units, so I've been on the lookout for a set of complete ZX spindles. Even better than just some strut assemblies though, I found a whole parts car a little less than two hours away.
The Suburban pulled it fine, despite the car not having a windshield and the closed rear hatch acting as a giant air brake. The engine temperature never exceeded 210 degrees, and the A/C blew cold the whole way up despite ambient temperatures above 95 degrees. My wife was watching the transmission temps with the COMPUSHIFT controller on the way back when we came to steep grades. It never got above 220 during long hills in 4th with the torque converter out of lockup. On the longest and steepest mountain pass, the highest the controller indicated was 248 for a minute while climbing in 3rd gear. Meanwhile the fuel gauge needle sank alarmingly fast. Tranny fluid still looked and smelled good after the trip.
Last week I finally got around to wiring in the trailer brake controller from my Grandfather's '88 C3500. Its a 90s vintage Tekonsha 2030 Mark 12 unit.
It did the job just fine. I'd pulled the lighter 510 around town on the same trailer before adding the controller and the difference in braking performance is well worth anything necessary to have it.
Previously I had already taken care of all the 7 way trailer wiring itself. The Tekonsha is powered from the '88 distribution block, through a 20 amp circuit breaker, and the auxiliary power to the trailer is done the same way, just run through a larger circuit breaker then routed up, inside the a-pillar, along the roofline and back down through the rear pillar to the trailer connector behind my license plate.
Now I'm all set to tow whatever comes my way in the future.