So as some of you know I picked up a 88 F250 with a 5.0 and M5R2. Today I was driving, where I live the wind is strong about 20 MPH, and in overdrive my truck couldn't go any faster than 60. In 4th it books it. On any other calm day I have to be careful because I speed even in overdrive. Is this normal with the 5.0 and M5R2? It's a great truck with no problems. Maybe I'm just fat and bogging it down lol

 

Does that truck have 3.55 gears perhaps? The 5.0 makes no torque below 2000rpm, that becomes very apparent in a heavier truck like an F250.

 

You could also have a clogged exhaust or catalytic converter that's sapping power. Or maybe a stuck brake? If you have an infrared thermometer (they're cheap on amazon and very useful), check the wheel temperatures. If one wheel is hotter than the other side you know you have a brake problem. An infrared thermometer might also be used to diagnose a clogged cat, but I don't know what temperatures you should look for.

When was the last tune-up? Filter change (including air and fuel)? PCV valve?

It could also be just low compression. How many miles? Have you done a compression test? Oil in the air filter box is a sign of excessive blowby, that's another thing to look for.

I almost forgot the obvious question... does it have larger than stock tires?

 

Andy has got some good ideas, check for simple stupid stuff like dragging brakes.

A mechanic's vacuum gauge would be perfect for knocking out a few of those tests, it would indicate a clogged catalyst right away, as well as low compression or other engine derangements or late ignition timing.

 

I drove a 5.0 f250 for 8 years, and it was the worst thing I've ever driven.

Feeling broken in overdrive is normal.

 

I don't think its had a tune up in forever. Odometer says 64k. So probably 164k. It has 3.55 gears. 89 I think your right lol

 

I'll also put my vacuum gauge on it

 

And it has larger tires. 285/75/16s

 

3/4 ton ...
headwind ...
fat tires ...
5.0 litre ...
29 year-old truck ... so probably more like 264k on it, with 364k entirely possible.

as stated, it's probably overdue for a tune-up, check for dragging brakes, put a vacuum gauge on it ... and hope for only slightly more performance.

 

I'll check for dragging brakes after work and more than likely do a tune up after payday

 

You're in Colorado too right? Factor in ~3% power drop per 1000' of elevation above sea level. The slowest vehicle I've driven in Colorado was a Ford 4.6L F150. Short stroke just kills torque output...

 

Oh yeah... elevation can be a HUGE power hit.

You lose *roughly* 3% power per 1000 feet elevation gain. So at 6,000 feet you're down almost 20% right out of the gate just because of the thinner air. I used to have a Bronco with a 5.8L and it was a dog in the mountains. Overdrive was only useful going downhill.

 

Jesus.....so I'm at 7800ft......wow i guess I don't feel as bad anymore. I didn't think elevation killed that much power

 

7800 feet!!!

Yes that's your problem. The power loss is substantial at that altitude! You wouldn't even recognize your truck at sea level.

Not that you might not need a tune-up or any of the other things mentioned.

This is why forced induction is so popular at higher elevations. My truck barely notices 7500 feet.

 

Yeah on average 7800ft. I would love to do a supercharger but to rebuild the lower to handle it then the s/c kit $$$$$$. I'm just glad nothing is wrong. In 1-4 I have great power climbing and stuff so I guess just only use overdrive on non windy days or when the wind is pushing me forward jaha