Car won't accelerate past 40mph

Torinosuke
Wed, 28 Jan 2015 09:33:57 +0000
Maintenance/Repairs

93 Mercury Cougar 3.8L V6 with just over 83,000 miles

l’ve been trying to figure out this issue for ages, but can’t seem to find the root of the issue. When driving and accelerating to 40mph, the rpms drop and GET STUCK at exactly 1000rpm. Forcing the accelerator down makes the engine bog and sputter and not go any faster. No check engine lights whatsoever.

The idle is very rough and low in park (700rpm compared to the regular 900) and very low in drive (500 compared to 650-750). When stopped in traffic for a while, it begins to shudder and shake like it wants to stall right there. Now let me run down the extensive list of parts l’ve thrown at it, bringing only temporary results:

Replaced catalytic converter
Replaced IAC valve
Replaced O2 sensors
Rebuilt transmission (runs great, so l’ve ruled that out)
Replaced 1fuel injector
Replaced MAF sensor
Replaced motor mounts
Cleaned throttle body extensively

I asked a guy at a Firestone and he said that l needed a valve job. Asked another guy at another place, he said l needed a fuel system cleaning. Asked another guy under a tree, said l needed a new speed sensor. Can anyone else please give me ideas of what could be the root issue? l was thinking carbon build up over 22 years maybe? Almost all 83k of those miles have been city miles…

This car is my baby, all l want is for it to be able to handle highway speeds without a hiccup. Please don’t tell me to junk it, or that the repairs are not worth the value, l have no interest in ever selling it. l’m keeping it and plan to see 100k hit the odometer and many more miles!

32 posts - 12 participants