Toilet bowl doesn’t fill after flush

I replaced the flapper, handle, lever, pop up/float device and water supply line and shut off valve. The tank fills fine when I flush and it will flush normal once but then after, only a little water gets filled in bowl so next flush fails, fills bowl with water, next flush works. What is my next step? Plumber wanted $1300 to swap out the leaky shut off valve so I have been DIY since and not sure next best step. It’s an old toilet and am open to getting a new one if that’s the answer. Thank you!!