I recently bought an 88 F-150 5-speed with an inline 6 and EFI.
No problems first couple of weeks, but today after a short highway trip (4 or 5 miles at 65-70 mph), the truck started jumping noticeably when I was driving slower on residential streets. I noticed it first in 3rd gear, I think.

Truck is driven about 15-20 miles per day, just to work and back.

Now I'm getting a jerky ride in most all gears, especially 3rd through 5th. Almost feels like I have to give it extra gas constantly at 55-60 MPH or it will just jump and shimmy like crazy.
The check engine light even flashed once or twice tonight.

Before I have to take it in and mess with a mechanic (which is looking inevitable), I hoped someone might have a clue as to what this problem sounds like.

I know it's a truck and it's going to drive like a truck, but this jerky, jumpy ride is not the way it has been driving. I am convinced there is a problem. My truck drives differently today than it has before.

Truck has close to 150,000 miles on it. I have maintenance records, things have been replaced, of course, but seems to have been decently taken care of. Guy I bought from never had any trouble, and I know him personally and know this is true.

 

I've got the same year truck and while I'm not one of the great mechanics, like some of the guys on this site, here's what I would recommend: buy one of those $30 code readers, a manual and an ohm meter. I've got one and its worked very well. Once you have the codes you have to go back and check the sensors using the ohm meter because one bad component creates a string of other things to appear as malfunctioning. Also, before I do all that, I'd repalce the fuel filter, air filter and run a a bottle or two of good fuel injector cleaner in it. Naturally i'd make sure the distributor cap, rotor, wires and plugs are good. These trucks are easy to work on. I've never had mine in the shop.

Here's what I've replaced, the MAP sensor, ECM, EGR valve, EGR valve sensor and the O2 sensor (naturally plugs, filters, wires...). I replaced the high pressure fuel pump on one ocassion when the truck totally shut down.

The jumpy truck is a lack of power which means its got a miss, most likely a fuel or ignition problem.

 

Check the plug wires. In fact, look over the repair records (or ask the guy you bought the truck from) when the last time the plug wires were changed - if ever. If it has been a while, it'll be worth the investment - and it's simple to do compared to dealing with pressurized fuel or costly readers - it's a start...

 

my truck has did the same thing on ocasions here is what fixed it for me

check the contacts in the distributor cap.
unplugg the green vaccume line on the EGR valve and then drive it to see if it fixes it. if so by a new EGR (or do like me and just leave it unplugged)
also check all the plug gaps (.044)

 

I have a 1989 F150 with 300 six and five speed trans and efi. I bought the truck with 110,000 miles at auction and it has always run jerky at anything under 1800 rpm in third thru fifth gear. It will accellerate hard and run decently in fifth at 65 plus mph. I know this truck should run smoothly in fifth gear on level ground at 45 mph. People that have ridden in it thought it was an electrical miss. The 02 sensor, throttle position sensor, egr valve, wires, cap, and plugs have all been changed. Compression is good, no smoke, passes smog barely. The truck now has 150,000 miles. I don't have the answer yet but today something very interesting happened. The temperature gauge quit registering so I went to buy a new heat sender. At the auto parts store I pulled the connector off the top of the sender unit, to get a better look at it, and went in and bought the new unit. I left the wires disconnected and when I drove home I thought I was in a new truck. Smooth in every gear and lurch free at 45 mph in fifth. I installed the new sender and the gauge still didn't work but the jerkiness returned. Weird. Pull the wires off your sender. Mine was at the thermostat housing. I would be interested to know if it cures the lurching in your truck. If I find the answer I'll let you know.

 

You changed the temp sensor for the ecm the temp sender for the temp gauge is above the starter. You need to run the engine codes and see whats going on.

 

Thanks. I feel really stupid. And the worst part is the parts guy tried to give me the right sender. Common sense told me the heat sender for the gauge shouldn't have anything to do with how the truck runs. I'll check the codes this week and purchase the correct sender.

 

I've got a 92 with this problem. What is the ecm and can you run without it?

 

ECM stands for Engine Control Module (i.e. the computer) &
no, you can't run without it.

 

Same problem, only in an F-250.

Here's what I have figured out,

1. engine lurches any time a major electrical load is applied. (ie headlights)

2. It gets better if I run mid grade fuel

3. I notice it more often if I am running on the rear tank.

I don't know if this help you, check and see if your problems match.

Wolf

 

Fuel grade, choice of tanks, or electrical load makes no difference in how my engine runs. Since I accidently disconnected the ECM heat sender the truck will run smoothly in fourth gear all the way down to 35 mph, smooth in fifth down to 40 mph. But the check engine lighe stays on. Checked milage today on a 220 mile highway trip at 65 mph, air off. Got 18.5 mpg. Before, the best I could get was 17, usually 15.5 to 16. I will have the codes run next week and report findings.