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1999 Toyota 4Runner — vibration under acceleration but not while coasting

CleanCommuter732Community StarterSep 12, 20251999 Toyota 4Runner SR5Atlanta
1999 Toyota 4Runner SR5, about 238,000 miles. The car is smooth at the same road speed when I lift off, but under moderate acceleration I can feel a vibration through the floor. What would you inspect first to separate axle/driveline issues from an engine mount?
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RoadTripEnthusiastCommunity StarterCommunity StarterSep 13, 2025permalink
Start with the test that can prove you wrong. Write temp, speed, and in-gear vs coast when the 1999 Toyota 4Runner does it — then decide on parts. Don't erase codes until someone who can help has seen them. A shop burned me once by skipping that step. I keep a notes app thread for this now.
TruckSeller240Community StarterCommunity StarterSep 14, 2025permalink
Yes, with one caveat: Write temp, speed, and in-gear vs coast when the 1999 Toyota 4Runner does it — then decide on parts. That's the branch I'd chase this week. On “vibration under acceleration but not while coasting,” that was the fork that mattered for me. That's the sequence I'd use. Checking again after work.
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