Changed timing chain tensioner and now car won’t go over 20 mph

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. Check for diagnostic trouble codes - if warning lights are on, codes are most definitely set and will be available for diagnostic purposes. I would wonder about whether something went wrong during the repair process. I would not expect your symptoms after repair if it was not doing taht before repair. What was the original cause of part replacement? Maybe a wire harness not fully seated after removal? I'd recommend a shop near you have a look to see what's going on, retrieve that trouble code and assist. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.