Help with random jerking during cruise

[crisp76]

Hello, some issues on my 87 when cruising during normal operating temperature 170-180, car jerks/miss fires. Runs ok when cold and on the Freeway 60-65. This has been going on for a year or so since I hardly drive the car. I have cleaned TB, MAF, IAC, new plugs RT43’s gapped at .035. Vehicle is mostly stock except for AFPR, TT Chip, 30lb injectors, Scanmaster and Hot wire kit. Nothing has really helped. Cross counts while cruising @ 15-25 mph the numbers went from 3-90 in 21 seconds. Is this normal count jumps? Also my Scanmaster readings warm in park as as follows

RPM 700-800
TPS .42
IAC 15-25
MAL 00
O2 730-760
AF 05
L8 38
BAT 13.6
INT 128
BL 124
MPH 00
CLT 173
ATS 99

 

[deezdad]

You said random jerking...

 

[deezdad]

Sorry the stupid idiots are in my algorithm lol.. I'll be following as these questions are usually good for learning. I'd try a can of royal purple max clean & fresh fuel filter for a quick shot in the dark.

 

[crisp76]

Forgot to add the fuel filter. It has been changed.

 

[vacuum 6]

Not the converter locking and unlocking?

 

[deezdad]

Stale gas maybe, how long since you filled it? My goober buddy bought a lawn tractor and filled it with bad gas wouldn't even start he thought he bought a lemon, fresh gas fired right up.

 

[crisp76]

The fuel is fresh. I do drive it every 2 weeks or so. Not sure about the converter locking and unlocking. Will it hesitate/ sputter @ 15-25 mph?

 

[mblum]

Stock MAF or modern MAF with a translator?

How old are the spark plug wires? If the are getting some age on them look for cracks or burnt spots on the wires and boots.

Also, what is the age of the ignition coil?

 

[crisp76]

Stock MAF with some MSD wires that are at least 10 years old. Not sure about the ignition coil, but I know it’s been replaced. I purchased the car a couple of years ago. The wires look good but I haven’t done a thorough inspection.

 

[vacuum 6]

The fuel is fresh. I do drive it every 2 weeks or so. Not sure about the converter locking and unlocking. Will it hesitate/ sputter @ 15-25 mph?

Stock locks around 15 MPH assuming youre using the OEM chip.

 

[deezdad]

He's running a turbotweak chip.

 

[crisp76]

Even with the factory chip, these symptoms were still present.