2007 f150 4.6 liter v8 2 wheel drive really struggles at any speed over 55mph the check engine light comes on and the motor shakes like crazy as if it’s in the wrong gear. The transmission is new and installed by ford and I had this issue before that and after. The cpm and all plugs and coils have been changed in the last 3 months. The trailer is about 3,000 lbs total tongue weight about 400-500lbs. Any ideas on what it could be? This problem only occurs when I pulling my boat. without the load it runs fine on the interstate. I was told maybe throttle body needs cleaned?

CEL goes off after I back off the throttle a bit no codes

No codes as the check engine light does not stay on and the coils and plugs were replaced by a ford dealership

There aren’t any pending codes or any stored from when the engine light came on. This is why I have so much trouble figuring it out. Ford says they want to have a mechanic take it home for the night but I’m not thrilled with some mechanic idk taking my truck and my boat home. That doesn’t seem like a very good way to find out. Test driving is one thing but that’s different.

Thank you for the suggestions I’ll check mas and throttle body to make sure it’s getting enough air and let you guys know in the am!