Perhaps someone out there can give me some good advice...My 1986 manual tranny 5000s (nonturbo, nonquattro) with about 300,000 miles is acting like it is choking down at 3000-4000 rpms. It runs well generally, but when accelerating under load (up a hill) or quickly, it will "bog down"--it literally won't exceed about 4000rpms. It also sputters sometimes when it is cold, until it warms up. I suspect this may be a fuel injector(s) problem or perhaps a fuel pump output problem, but suspect it could also be an air or ignition problem. I can accelerate slowly even up a hill and maintain speed limit, but the car just doesn't have any punch or "umph" in acceleration.

I've done the normal routine maintenance stuff on it since I've had it for the past 10 years, including changing the ignition coil and plug wires, as well as the plugs, distributor cap & rotor every 2-3 years. I've also replaced the cold-start valve, throttle switch, and cleaned the air intake & MAF area, and replaced some of the temp sensors/senders and have a K&N high flow air filter. I have run several tanks of fuel injector cleaner thru and have replaced the fuel filter several times as well, including just recently. I am planning to send off the fuel injectors to get them cleaned soon to help with performance and possibly rule out this as the culprit in my acceleration. Does anyone have any "likely solution" troubleshooting tips for me?

Thanks much in advance!
BGaudi5000s