89 gmc performance

So customer dropped of his 89 gmc 2 wheel drive pickup with the 350. It run but very poorly. It almost seemed to be flooding it's self. Well I figured it might be the coolant sensor. So I let it sit until I had a little time to go screw with it which was about 2 hours. Well that pickup would barely run now it was bad enough you couldn't put it in gear or it would die.

Well I decided to peak under the cap. Woof that looked terrible. So new cap, rotor, and ignition module. Put it together, reached in and hit the key and it fires right up. It runs but not well. It has a miss to it but hey it runs on its own except if you try and give it any gas it will fall on its face again like it's flooding.

I run out of time to screw with it. So today I bust out my multi meter and do some poking around. The coolant sensor does test good. Injectors test well.

Where shall I go from here. A guy in town whom I trust said the fuel regulator.

Is there something I'm over looking here. Now that it runs it runs a bit rough. It will run at idle on its own kind of. It's more of a sloppy idle where it's always hunting for a good idle speed. It revs up a bit then it will start slowing down until the computer kicks in and speeds it back up. If I try to speed up the motor it starts to cough and stumble like it's flooding.

Map sensor, EGR stuck open?

Is the 'engine light' ON? If so, get the scan code.....it'll 'point' NOT telll you where the problem is, maybe,hopefully...

My 88 suburban ran horrible when I bought it. It would toss a o2 code but nothing else. I changed the coolant temp sensor that helped some.follow all the plastic vacuum lines and replace any that are suspect. Tha TBI is abigimprovement over a carb but the OBD1 dosent help when trouble shooting. It's kinda stupid and soft faults reset themselves without keeping a record of it

what you decribed sounded like one of my vehicles years ago....was a parcial flat cam

I second HubertGA's suggestion, throttle position sensor.

I have not checked the timing for one simple reason. He said this come on all of a sudden. Which to me I would lean to a bad sensor. Maybe I'm thinking wrong about that.

Tomorrow I'll build a jumper harness so I can check the throttle position sensor.

I did try a different map sensor that I had sitting on the shelf. It was used and I hope I didn't keep an old junk sensor. But any way that didn't help.

Take the Neg cable off the battery for awhile.  When you reconnect it that should reset any faults.  And like was mentioned,a good ground to the body and the engine.

OH the good old days,flat cams,the early carbon wires that the insulation would crack on or the carbon itself would break. All good fun.