weird you would ask me, on my page, but ill try to answer.
Many reason would cause delayed shifting,
1 Old transmission Fluid, do a tranny flush, change the filter. use OEM recommended fluid, Fluid may smell burnt or look black or lost Reddish color.
2 Low Fluid, Let the engine get hot, Check fluid level while engine is running, add if needed, Sometimes too much can cause issues.
3 PCM could me running in Limp Mode, u can google issues involving Limp Mode but is dosnt sound like your Issue.
4 Could just be too old and nearing complete faiilure, Rebuild it or get a new one. Pricey but guarantees no issues.