no acceleration past 70mph

ok guys im losing my mind first off i have an 07 2.7l manual tacoma. its on 33'' tires with 4.88 gears. it will not accelerate past 70mph under the slightest load such as a hill or even wind. so far i have replaced the fuel pump with urd pump, cleaned throttle body, new spark plugs, cleaned maf, hollowed out my cats and swapped the air filter. what else could this possibly be? i should be pulling good power and torque on gears alone. any help much appreciated.

 

Spark plugs gapped correctly? When did you notice this problem?

 

does the engine seem like its idling smooth? Any CEL flashing or steady?

 

yep, proper gaps. its always been there but i thought it was just being stock gears and 33s. i noticed it severely last month driving to the mint 400. head winds and hills had me at 55mph in 4th gear at 4500 rpm

 

idle is fine, no cel

 

Have you tried a smaller tire? 33" might be too much tire in 4th for 4cylinder

 

not with 4.88 gears. my buddy runs the same drive train in an access cab with 35s and smokes me.

 

When did you change your fuel filter last?

 

hmm could be clutch slipping possibly..

 

last week when i went to the higher pressure pump

 

clutch was replaced last month

 

did it have this same problem before you replaced the clutch?

 

yes, foot to the floor up a hill and wont budge in rpm or speed, just slows down

 

Partially clogged converter is a high probability. It will get worse.

 

both cats are hollowed out, i know all the environment tongue lashing but relax, new cats are on the way.

 

That's odd, I can pull last past 70 with 35's.

Interested in hollowing my cats

 

i know, shouldnt be an issue but it is under any small load. took me 30 minutes to hollow them out with a 3lb sledge and 3/4'' pipe

 

W/o considering the lousy aero of the truck, that's mathematically 90.

Only time I've experienced something like this (higher RPM/Speed restrictions) on an otherwise fairly decent running vehicle are...........

Timing is way retarded

Fuel filter is partially clogged

Cat or muffler is failing internally creating an exhaust restriction. Some combination of all these.

I know you've addressed most of these points, I'm just reiterating experience.

Does it pull hard (good) up to the ECU fuel cut in the lower gears? I'm guessing not, although it may be 'normal' streetable?

 

Have you checked your compression? Have you checked your ECM for codes or check your values on sensors are in spec. Almost sounds like a worn out motor from your post.

 

do the brakes seem like they are dragging?