No throttle response, keeps cutting out

I have a 1990 5.0 lx. Fuel injected. Recently i have been having problems going from 1st gear to 2nd gear with the throttle. Right when i get ready to shift from 1st gear to 2nd the motor starts to choke and spit and sputter. then when i get into 2nd gear my motor is at idle but i have no throttle. I pump the gas a couple times and smell pure gas, then the motor starts to pick up and spits and sputters and then i have throttle again. It only happens from 1st to 2nd gear and doesnt happen all the time. Just random. I went 2 weeks without it happening then today it happened 4 times. Anyone having similar problems or a poss fix? Poss a throttle sensor? or im all out of ideas, first i thought it might be the fuel filter...but it doesnt happan all the time but now seems to be getting worse. any help or things to look at?  

Wow, that's a doozie. You're really going to have to put on your troubleshooting hat for this one. I would start with the intake tract. Specifically, the intake tubing from the filter all the way to the throttle body. Check and clean your mass air meter, and make sure everything's tight. If there's an aftermarket ignition on the car, there could be something going with that, as well. Let's see a rundown of what's done to the car. That may help us diagnose the problem. Thanks.  
Michael Johnson
Associate Editor
5.0 Mustang and Super Fords

I bought the car 7 months ago and have not had any problem like this till recently. it has a k&n filter but stock intake. Holly Systemax intake, b303 cam, dump h-pipe exhaust with flowmaster 40 series mufflers. When i bought the car it had a lot of things not hooked up. Looks like new steering column. Im not even sure if its the original motor in the car. It took about 2 weeks to button everything up. I think i might just fix the problem by changing the motor over to carb. Much easier to work on, than the computers and sensors.  

wow!!! hold your horses!!! switching to carb will be an idea but i think that the problem is under your distributor cap. under the cap sits your rotor the metal cap under the rotor is called the stator. if you mark the holes with a marker or scribe to be sure of its position you can remove the two small bolts that secure it in place. pull it up and flip it over. if its wore then check the small pointed pickup that the vanes of the stator travels through if it moves or looks like it madecontact the the stator pull the distributor and rebuild it or replace it. let us know what you find. if thats not it ill give you one more thing to check.  

It has a MSD distributor and all new. Do you think that it could be in the mass air? A couple people told me that might be where i should start. I unplugged everything to make sure i was getting connection and nothing was shortening out. Im in the couple weeks where the car is running strong with no problem. So as soon as it does it again that will be another thing that i can cross off the list as to what could be wrong. Thanks for the help.  

Another thing that i have noticed is when im driving the car and i get on it when i shift no matter what gear im in it hiccups. Just like it would do after i put it in 2nd gear no throttle..but its just a quick sec and the motor is back. I don't know if that has something to do with it or not. But like the other it doesn't happen all the time just periodically.  

I see the last reply was almost 3 months ago. I'm wondering if the OP has found the problem.

I had a similar situation and it ended up being a bad spark plug.

I bought those fancy (and expensive) Denso irridium plugs and installed them on a '95 GT. Apparantly, the tool I used to adjust the gap left a nick on the terminal and created a hot spot. After many hours of driving, it eventually burned right through the terminal, leaving a nub that the spark was trying to jump to. At initial WOT, it didn't respond very well.

Hope this helps.  

I've seen several post regarding the ecu swap with the dealer. I also have a friend that is a yamaha factory rep. I've discussed my issue with him and he doesn't agree that it is the ecu. Thinks it is something else.

Here are the present issues:

   * No throttle response between 5000 and 7000 rpms in all gears
   * After passing 140mph, letting off throttle, drop down under 100, attempt to accelerate again and get short cut out(almost like my Generic Viagra  hand slipped off the throttle)
   * On several occations, pulling up to a stop signal, pull in the clutch and bike dies.


I've talked to the dealership and we are looking up the criteria for the swap.
Wondering if cut out is related to no response issue.
Attempted tightening the clutch, seems to have stopped the stalling.  

I collected an 02 Speed Triple last week. 17k on the clock.

Rode it 35 miles home and all's fine.

Filled the tank up today and went for a ride,got some Cheap Generic Drugsand other stuff at the mart,i saw someone looking at my bike ,kind of close . After about 50 miles the throttle response off idle starts to get really poor - almost like a choke left on. Motor cut out once coming to a stop, otherwise it's just really fluffy until 3k when it goes fine.

Idle is steady if maybe a little low. No MIL light.

Any ideas? Bad fuel maybe?Or some damn sand