I have a 1995, 80 avante 2.0e with 148000 on the clock (14000 of which are mine in5 months) over the past few days it's lost power in all gears and last night i noticed that if i floored the throttle (gas pedal ? ) above 85-90 mph it starts misfiring & slowing down, but a couple of times when i happened to be going downhill it would barely scrape a 100 (2 weeks back i could see almost 120 on the clock if desired).
I fitted new plug leads last week to cure misfire at idle caused by cleaning the engine down to find oil leak (turned out to be burning it one way or another.
I will be under the bonnet/hood in about 7 hours so any ideas will be appreciated
thanks

check that all vacuem is good. clean throtle body too. do a compresion check to see if the engine burns oil. check the spark plugs if they burn mixture right, like if they are white, is good, if they are black its bad. check regular stuff like air filter.
does the engine have problems when standing still?

Sounds like converters are plugged