Random cylinder misfire

Vehicle listed above has the ecoboost. So back track a little about 6 months ago was having issues with car while on road trip check engine light came on. Came up as a random cylinder misfire. Carried on made sure had oil and it wasn’t burning just to be safe (had to add coolant multiple times though) get back take it to shop come to find out coolant was getting into the short block. So as it should be car was under warranty the shop replaced the short block got it back no issues well shortly after light came on again and was blinking this time. So called same Ford shop and they brought it in and there was an engine knock so they replaced the long block this time. So short and long block are brand new (not even 3 months apart this happened). So go to drive it and it randomly slows down and won’t go above 40 (this happened with no check engine light on) makes it hard to diagnose. Well finally check engine light came on again for same code in beginning random cylinder misfire. I feel like the shop is looking in the wrong place now and there’s something wrong with the cars computer throwing things off? Could this be it? Could it be something else? I’m tired of dealing with this shop they have no been nice so if I can get idea what this is to take somewhere else and get it done that’d be helpful.