Hmm you checked everything did you get your exhaust checked?
Make sure none of your wheels are jam.
I had a 2E engine in my car before i switched to 1.5 5AFE engine and i use to have kind of same issue. Car use to go to max 120 or 125 that also when road was straight with not much climb.
Now going from 100 to 120 was tough some time on the other had a friend having same engine use to touch 140 easily even though my engine had everything in perfect order.
Not to mention we also tried everything in the end swapped the engine with 5AFE.